A PORTABLE MULTI-CAMERA SURVEILLANCE AND MONITORING SYSTEM FIELD OF THE INVENTION This invention relates to video surveillance equipment in general. In particular but not exclusively, 5 it relates to a portable, rapidly deployable, multi-camera surveillance and monitoring system having indoor and outdoor applications. BACKGROUND OF THE INVENTION There is a well acknowledged need in contemporary society for security of temporary and/or 10 outdoor premises such as constructions sites, mine locations and various venues for special events which are often left unattended or require security guards to patrol them. Prior art surveillance systems include the following: 15 US 7852211 discloses a trailer-based mobile surveillance system applicable to the monitoring of outdoor sites and locations. US 8007189 describes a single camera on a portable tripod using an internet protocol to run a network video recorder to stream live video to a remote station. 20 US 12/794, 737 discloses the portable deployment of a single camera for indoor application with remote live-access to video streams captured by an analogue camera. - 1- In addition, there are also video-snapshot products that use a passive infrared detector (PIR) attached to a camera to detect movement, capture a short (e.g. 10 seconds) video clip and then transmit this to a monitoring centre via a mobile broadband based protocol for example, via GPRS, 3G or 4G communications. 5 While the abovementioned prior art systems go some way in providing solutions to the need for surveillance they also have disadvantages and limitations. In the case of the video snapshot prior art, there is no provision for full-time video recording or remote access to live video which makes it impossible to confirm whether persons are still present on site. Furthermore, these systems 10 only support a single analogue camera and a single PIR based detection sensor. They also cannot limit the field of view monitored by each detection sensor and are therefore vulnerable to false alerts. In the case of trailer-based systems, the following deficiencies have been identified. The 5 requirement of a trailer vastly limits the locations in which the surveillance system can be deployed. These are generally large and heavy systems and can only be deployed where the trailer can be towed. Other limitations to these systems include a lack of provision for live two way audio or other sensor inputs to detect intrusion events, such as PIR sensors, contact switches and perimeter security devices. 20 In the case of tripod-based devices, the following limitations are identified. The tripods require a relatively stable and horizontal surface. Tripods are also easy to steal and/or damage. Most tripod systems are usually based on a single camera mounted to the tripod and physically connected to the control module. -2- These systems also do not include any live audio output capability or an uninterruptible power supply to ensure ongoing operation in the event of power failure. 5 Prior art single analogue camera systems are also usually not designed to be deployed in outdoor situations. They are generally comprised of a single camera that is hard-wired to the control module. Analogue cameras are also restricted in their image resolution, require expensive cabling, and cannot be installed wirelessly. 10 OBJECT OF THE INVENTION It is the object of the invention to ameliorate some or all of the above disadvantages of the prior art by providing a novel and innovative portable surveillance system or to at least provide the consumer of such devices with an alternative choice. 15 STATEMENT OF INVENTION In one aspect therefore the invention resides in a portable surveillance and monitoring apparatus including: one or more internet protocol (IP) cameras adapted to capture a moving video image; a computerised software driven control module adapted to process the video data captured by the cameras and detect site intrusion events wherein the control module in communication with 20 other control modules comprises with the cameras, a local surveillance network wherein in operation intrusion events can be transmitted by the control module to a remote server or receiver responsive to the event and wherein a control module in communication with other control modules, having the strongest transmission and reception signal assumes the role of a master controller co-ordinating the operations of the other control modules and the cameras. -3- Preferably, the portable surveillance apparatus of the present invention includes one or more intrusion detector sensors responsive to movement(s) of an intruder. 5 Preferably the controller or control module establishes a local communications network for both wireless devices and wired devices including power-over-Ethernet (POE) connections, e.g. for use by cameras. Preferably, the control modules and the master controller are in wireless communication with 10 each other. In the alternative, the modules can be hard wired together in the surveillance network. Preferably, the wireless communication between the modules and also between the modules and the cameras is via a wireless communication protocol. 15 Preferably, the control module automatically detects the IP cameras that are connected to the local network. Preferably, the control module establishes internet communications for transmitting intrusion 20 events and providing external access using wireless broadband networks such as 3G / 4G or by satellite. Preferably, the control modules are adapted to provide full NVR facilities such as real-time display of video feeds from the cameras and recording and playback of video feeds. -4- Preferably, the control module also provides access to network video recorder (NVR) features both locally and remotely over the internet to authorised users. Such that, local users can view the video using any network connected device; and/or remote users can view the videos through 5 any internet-connected device. Preferably, the control modules provide two-way audio facilities over the internet, using audio inputs from cameras or a dedicated microphone and sending audio output to one or more speakers. 10 Preferably, the controller or control module monitors all components in the system and provides updates on their status to a remote monitoring server over the internet, so that any interruption to the system's operation can be acted upon. 15 Preferably, the controller or control module provides local users with secure access to the internet for local site use. Preferably, the controller or control module permits secure, authorised remote access to control all settings within the control module and to upgrade the software components. 20 BRIEF DESCRIPTION OF THE DRAWINGS In order for the invention to be better understood reference will now be made to the accompanying drawings, wherein: Figure 1 shows components of a preferred control module. -5- Figure 2 shows the information flow between components of the invention. Figure 3 shows the communication paths between multiple control modules, Figure 4 shows the exterior casing of the control module; and Figure 5 shows a table of the various components shown in Figures 1-4. 5 DETAILED DESCRIPTION OF THE DRAWINGS Referring to Figure 1 there is shown a control module (1) comprising a rugged, waterproof case adapted to house electronic equipment. The control module being preferably in wired or wireless communication with internet protocol cameras (12,13). The control module can be secured to any 10 structure such as a power pole, tripod, building or any other support with minimum effort or skill. The cameras are similarly easy to install and may be hardwired via network cables (36) to the control module, e.g. using Category 6 POE cables. In the alternative, the cameras may be in wireless connection (40) with the control module. The control module establishes communications with remote receivers or servers via a mobile broadband or satellite connection 15 Operation and Information flows The operation of the invention and the information flows are described below, with references to Figure 2. 20 The invention establishes both external and local communications links. Externally, communications occur through the internet (39), via 3G/4G mobile or satellite links or other available communication technologies. Locally both wired Ethernet and wireless networks are established. The invention can thus provide internet communications for both surveillance purposes (52, 54, 55) and for general computing needs of local users (50, 51). -6- The computer (10) in the control box runs full-featured network video recorder (NVR) software to provide the surveillance facilities of the invention. The invention also includes software to detect when cameras are connected or disconnected and to automatically add or remove them from the 5 NVR configuration accordingly. The NVR software records and monitors the real-time audio-visual streams (63) from the cameras (12, 13). Audio-visual streams are recorded (62) to the storage drive (11) and this can be done on a 24x7 basis due to the large storage drive capacity. Selections of video recordings and pictures 10 can also be transferred (71) to remote storage (53) according to pre-defined rules. The NVR software has a schedule that determines when video streams are monitored for intruders. During monitoring periods, the NVR software analyses real-time video streams for movement; motion detection can be limited to one or more areas in each camera view and 15 advanced motion detection algorithms can be used to identify particular shapes, missing objects etc. If motion is detected, the NVR sends alerts over the internet (70) via SMS, email, FTP, instant message, voice message or direct to a web service. A picture or short period of video can be sent with these alerts. These alerts can be monitored by individuals (54, 55) or by a commercial surveillance monitoring centre (52) to allow appropriate action to be taken. 20 Intrusion events can also be generated by other input sensor devices (14, 15, 16).On receipt of these sensor alerts (66) through the general purpose input/output (GPIO) ports (37), the software can both trigger video recording (62) and send site intrusion alerts (70) using the range of mechanisms listed above. -7- The NVR provides viewing features to authorised users both locally and remotely over the internet (39). Local users can use a browser on any network connected device (50, 51) to view both real-time audio-visual streams and audio-visual recordings (74). Remote users can use a 5 browser on any internet-connected device (54, 55) to view both real-time audio-visual streams and audio-visual recordings (72). The invention also includes software to provide two-way audio facilities over the internet (72, 73). Audio inputs are obtained from camera audio-visual streams (63) or from a dedicated microphone 10 (46, 77). Audio output from remote users is sent to one or more speakers (48, 78). The computer (10) and router (42) are also configured to allow authorised remote access to the computer to control all settings within the control box and to upgrade the software components. Authorised users can connect to the invention to control its configuration both locally (51, 75) and 15 remotely (55, 73). The control box is kept secure by the use of firewall and VPN (for secure authentication and encryption) afforded by the router. Software is included to monitor the state of the control box and associated components. This software sends equipment and software statuses externally (76) to a remote network monitoring 20 server (56) using a standard protocol. Example items that would be monitored are the loss of external power (21, 22), low battery level (20), NVR software not working, cameras not working or removed (12, 13), blocked camera images, control box opened/compromised, high and low temperature alerts and shut-down situations caused by temperature extremes. In addition, an absence of regular statuses (76) would be interpreted by the remote monitoring server (56) as a -8malfunction of the control box, either through failure or interference by criminals, allowing appropriate reactive steps to be taken. This is a vital feature in any surveillance system. The inclusion of a general purpose computer allows extension of the invention with a vast range 5 of other features that can be supported in a general computing environment. Examples include GPS tracking, vision analytics, local printing and email, site-specific software for customers and so on. Multi-box capability 10 The multi-box capabilities of the invention are described below, with references to Figure 3. The invention supports interconnection of multiple control boxes at a site via wireless or wired connections (82) to provide a single, combined surveillance system with redundant control and communication functions. 15 The invention is designed so that the control boxes will identify each other when in a mesh configuration (82) and will automatically determine which control box will become the 'master' box for communications (80); all other boxes become secondary control boxes (81). The master control box provides the primary external communications link (83); other boxes can provide secondary external communications links (84). This arrangement provides superior 20 communications flexibility and reliability whilst providing a single inbound connection point for remote surveillance purposes. -9- External features The physical and environmental capabilities of the invention are described below, with references to Figure 4. 5 The invention is designed to be portable and easy to install. An unskilled person can secure the control box to any structure (power pole, tripod, building etc), install cameras and attach the camera network cables (36) to the control box. The case (1) is of robust construction to facilitate regular transport and resist intentional damage. It is the size of a typical toolbox with a carry handle (6). Internally there is also cushioning to protect the components during transport. 10 The case has mounting side plates moulded into it as a single piece for structural integrity (7) and restraining holes are included to enable the case to be securely bolted or cabled to a fixture, thus reducing the possibility of theft. A variety of mounting brackets can be added (8) to cope with different mounting situations. 15 The case is designed to cope with cold and heat through the inclusion of insulating materials, fans for airflow (2, 4) and optional heating and cooling/dehumidification elements (5) for extremes of climate. The case is designed for outdoor deployment, with all external junctions and connectors designed 20 to prevent the ingress of moisture (2, 4, 21, 22, 23, 31, 34, 35, 38, 45, 47). Connector covers are also provided for when connections are not used (31, 34, 35, 38, 45, 47). It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to - 10persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is herein set forth. In the specification the terms "comprising" and "containing" shall be understood to have a broad 5 meaning similar to the term "including" and will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the terms "comprising" and "containing" such as "comprise", "comprises", "contain" and "contains".