Emergency Manual Switchboard System

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 telecomm infrastructure was run by the GPO / Post Office Telephones and very different from today's networks. See the separate topic indexed the bottom of this page.

Most local calls could be dialled directly. Automatic long distance dialling (STD) was being introduced. Outside the main cities, customers dialled the operator, who then connected the call 'Manually'. Major towns had an automatic exchange known as a Group Switching Centre (GSC). Often there was a co-located Auto-Manual Centre (AMC) which housed operator switchboard positions handling assistance, directory enquiry and 999 calls for the local GSC area. Many AMC's had an EMSS too.

Emergency Provisions

To prevent overloading the network during an emergency or the run up to war, provision was made to disconnect all but essential telephones. There were 2 levels of disconnection, category 3 lines and category 2 lines. Preference Category 1 could not be disconnected. This may sound harsh, but often the network could not cope with normal traffic and engaged tone was very common. 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 covered with metal 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 circuits to be switched from the 'Normal' Switchboard to the 'Emergency Manual Switchboard' in the basement. Similar arrangements existed at other exchanges with operator switchboards.

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 there were two groups of numbers designated 'Civilian' and 'Military'. There were dedicated bothway lines to Leamington Spa, Leicester and Peterborough EMSS's. These were not used for day to day traffic. Provision was made to directly connect external lines from field telephones or switchboards in bunkers. In Kettering, none of these Trunk Subs, were connected at the time.

The EMSS room contained ration packs and beds, but the toilets were down a corridor, there was no strengthening or blast door. Much more suitable accommodation was provided when the EMSS moved into the new 1980's building.

Service Provided

I can only speculate on the service it would provide. Nobody locally appeared to have any instructions, but it was assumed these would be issued if the need arose. Regular speaking and calling tests were performed with the circuits switched to both the 'Normal' and 'Emergency' switchboard. There was a circuit to the Area War Group (AWG) at Leicester Wharf Street exchange. Its function was known to me at the time, but I believe it had a co-ordination role.

It is assumed that the appropriate 'Military' or 'Civilian' number would be issued to people or organisations allowed to use the service. If the telephone service were cut off from ordinary subscribers (Pref Cat 3), the lines from public phone boxes (Pref Cat 2) and selected users (Pref Cat 1) would still have service. Assuming the automatic network was still working, the EMSS number could dialled from a line that was not cut off. 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.