London alphabetic telephone exchanges - is there a map?
 

I'm researching a major British engineering group and am trying to put numbers to sites. Confusingly some sites have telephone numbers from two different exchanges.

Does anyone know of a map, descriptive text or website which identifies the geographic location/boundary of the pre-60s alphabetic exchanges - for example: CENtral, GERrard, LANgham etc. I know I can convert them to STD numbers, but that doesn't solve the problem!

Barry

Re: London alphabetic telephone exchanges - is there a map?
 

There was nothing unusual about premises in a geographical area being served by more than one exchange. It was simply a case of two or more exchanges being in the same building and having access to the same local line pairs.

Re: London alphabetic telephone exchanges - is there a map?
 

In times-past it was quite common for businesses spread across several sites within ten miles or so to rent 'tie lines' from the Post Office (which in later times would have been called EPS8 or EPS25) - so people at the sites could place [through their company's outward-facing telephone-operators] calls to what were essentially 'remote' extensions.

As a result, you could be able to call the outward-facing operator at site X and ask for a number located at site Y - if there was nobody else using the 'tie-line' the operator could put you through. There were various 'unofficial' kludges done which allowed you to directly-dial extensions across tie-lines through such company switchboards from the outside.

I temember a company called "Telephone Rentals" who provided semi-automatic switchboards that enabled this, much to the annoyance of the GPO.

Re: London alphabetic telephone exchanges - is there a map?
 

This may help

http://rhaworth.net/phreak/tenp_01.php

For example, MANsion House, METropolitan, and MINcing Lane are all listed as (Monument) so may have been located together in a very densely-telephoned area, and LONdon Wall and NATional are both listed as (Moorgate) - there was also a MOOrgate exchange.

Re: London alphabetic telephone exchanges - is there a map?
 

Thanks Oscar Foxtrot, that's perfect for my needs. Thanks to the others too - I was indeed aware of tie-lines and (very) remote extensions!

Barry