Background

This topic describes an emergency communications system known as the Emergency Manual Switchboard System (EMSS) introduced circa 1962 (about the same time as WB400) and removed at the end of the cold war in the early 1990's.

In the 1960's the UK telecomms infrastructure was run by the GPO / Post Office Telephones and very different from today's digital networks. Most local calls within a radius of 20 miles could be dialled directly. Automatic long distance dialling known as Subscriber Trunk Dialling (STD) had been introduced in Bristol in 1958. The national rollout took in the region of 20 years. So by 1962 other than in the main cities, customers wanting a call over 20 miles dialled the operator who then connected the call manually. Major towns had an automatic telephone exchange known as a Group Switching Centre (GSC). This exchange switched customer dialled called for the local area. Often at a GSC there was a co-located Auto-Manual Centre (AMC) which housed operator switchboard positions handling long distance calls, directory enquiry and 999 calls for the local area. The EMSS switchboards were located at an AMC to provide switchboard operators to staff it.

 

Emergency Provisions

To prevent overloading the network during an emergency or the build up to war provision is made to stop outgoing calls from all but essential telephones. This is known as the Government Telephone Preference Scheme (GTPS). There are two levels of disconnection - Preference Category 3 lines comprising of the majority of residential and business lines. Preference Category 2 lines. Public call boxes, public utilities, schools and council premises for example. The Preference Category 1 lines like Police and Fire stations, council bunkers have no disconnection facilities. All lines regardless of their category can receive incoming calls. So even with the maximum level of disconnection enabled a Category 1 line would function normally as they could still make a call to a Category 2 or 3 line.

This may sound harsh but in the sixties and seventies often the network could not cope with normal traffic and engaged tone was very common. Even as network capacity increased to present day standards such things as voting for a reality television show can easily overwhelm it. In the digital network an additional software tool known as call gapping is used to reduce the peaks of calls to voting or other special numbers. The GTPS still exists in the landline network and a similar arrangement, the Access Overload Control System (ACCOLC) is in place on the mobile phone network.

If normal operator services were suspended, provision was made to continue with a skeleton service. At Kettering AMC, where I worked in the 1970's, three or four of the thirty 'Normal' switchboard positions could be enclosed with steel RSJ reinforcing. This was stacked outside the window under a tarpaulin ready for deployment.

In the basement there was a single position EMSS switchboard. A group of keys allowed special emergency circuits to be switched from the 'Normal' Switchboard to the 'Emergency Manual Switchboard' in the basement. Similar arrangements existed at other exchanges with automanual centres.

This picture shows the type of switchboard used for EMSS. There are three operator positions in this example, each handling up to nine calls. Calls were connected using plugs on the ends of cords. At Kettering exchange there were two groups of ex-directory numbers designated 'Civilian' and 'Military'. There were dedicated bothway lines to Leamington Spa EMSS, Leicester EMSS, Leicester telephone Area War Group and Peterborough EMSS. These were exclusively for emergency use and not for day to day traffic. Provision was made to directly connect external lines 'Trunk Subs' from field telephones or switchboards in bunkers. In Kettering, none of our Trunk Subs were active at the time I worked there but they could easily be connected during the build up to war. However Regional Government and Royal Observer Corps Headquarter did have active lines to their nearest EMSS. I have received correspondence from a person at a ROC HQ that plugged in and called the EMSS and received an answer.

The 1960's EMSS room in Kettering contained ration packs and beds, but the toilets were down a corridor, there was no strengthening or blast door. Much more suitably protected accommodation was provided when the automanual centre and EMSS moved across into the current exchange building, built in the late 1970's.

 

Service Provided

I can only speculate on the service the EMSS would provide. Nobody locally appeared to have any instructions but it was assumed the Area War Group (AWG) would issue these if the need arose. Regular speaking and calling tests were performed with the circuits switched to both the 'Normal' and 'Emergency' switchboard.

In the sixties, seventies and early eighties Post Office Telephones / British Telecom was organised into telephone areas and regions. The Leicester telephone area of which Kettering was a part had its AWG in Leicester Wharf Street exchange. The function of the AWG was to co-ordinate the emergency response. AWG switchboards had links to other areas and the Regional War Group in the Regional Headquarters in Birmingham.

In the run up to war the appropriate 'Military' or 'Civilian' ex-directory number would be issued to people or organisations allowed to use the EMSS service, these people or organisations would have Category 1 preference on their lines so they would still make calls if it was necessary to restrict the service to non essential lines. Assuming the automatic telephone network was still working it could be used for local calls and for long distance calls that could be dialled by Subscriber Trunk Dialling ( STD ). It wasn't until the late 1970's that STD gave access to the whole country, before then, it was necessary to dial 100 for the operator who would connect the call to those areas not fully connected. Calls requiring operator intervention would have to use the EMSS telephone number. If the lines were switched to the normal switchboard, these calls would be answered with priority over normal operator calls (if any were still allowed). If switched to the EMSS, they would be answered and extended around the network using lines between EMSS switchboards to their final destination.

 

GTPS and ACCOLC

The EMSS network and switchboards closed in the early nineties at the end of the cold war. The GTPS and post cold war ACCOLC for mobile phones still exist and are likely to continue in one form or another. This should not been seen as anything sinister. In the past it has been necessary to use the GTPS when telecommunication equipment has been accidentally damaged to ensure the emergency services can still function.

At the time of the Electricity Generator workers' industrial dispute in the early 1970's I recall working by battery lights during a power cut to ensure the correct level of preference for emergency lines. However it was never necessary to use the Preference Scheme in Kettering as our emergency generator never failed.