In the early 1950s London Transport had one of the UK's largest private telephone systems in Britain, that covered not just the railways and head offices with automatic equipment but also trams, trolleybuses and the bus network.

Telegraphs and later telephones were well established in the steam days of the Underground. Telephones had also been installed during tramway electrification. Although road services no longer use an 'internal' network the railway network has now developed into a most modern and advanced system; it is a PABX for all practical purposes but over which network some very specialist communication is carried.

Also covered is the development of the LT radio network and some other cognate systems.

The London Underground network is still 'stand alone' (though highly integrated with the PSTN) while the London Transport organization has been integrated with the 'Transport for London' organization.

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