Enfield CB1

'Rubber knees?' was the alternative salutation which occasionally replaced the regulation 'Number please?' as the standard answering phrase on a typical GPO switchboard.

Photo: Enfield Manual Board when it was on display in the Dugdale Centre © LSA July 2012.

History

Enfield CB1 had 65 positions of the 'A board' and 11 positions for the 'B board'. It was the last manual exchange in Greater London (London Telephone Area) when it closed on 5th October 1960.

However, the last manual exchange in the London Telecommunications Region (LTR) was Upminster (Essex), converted to TXK1 (Crossbar) in 1970.

And the last manual exchange in England was Abingdon (CB board) in Oxfordshire, which ended its service at 07.00 hrs. on Thursday 26th June 1975 and was also replaced by a crossbar exchange.

The last manual exchange in Britain was a CBS2 (Central Battery Signalling No. 2) in Portree, Isle of Skye, on 14th October 1976 and also became a TXK1.

On the Board

The (Central Battery) CB1 'Sections Switch' was introduced into the UK as early as 1901. Each section of three positions had a total of 17 cord circuits.

The 'A Position' sections were for Subscribers' lines. The 'B Position' sections were for incoming junctions.

	"Number please?" This was the standard salutation with which an operator in the 1950s answered a call. Photo: An operator's breastplate transmitter and headband receiver © Light Straw Archive July 2012. Note the large jack, which plugged into a socket on the front of the switchboard.
	From about 1960 onwards these rather large plugs and sockets began to be replaced with a smaller version as the lightweight headset was introduced. Photo: ...plugged into one of the large twin jacks on the front of the switchboard © Light Straw Archive July 2012.
	Top to bottom: Outgoing multiple to local subscribers, Outgoing junctions to other exchanges, Calling subscribers (answering jacks). Photo: The Jackfields © Light Straw Archive July 2012.
	The Keyshelf, including ten white 'order wire keys' with letters and numbers corresponding to a telephone dial, viz ABC, DEF,... Photo: The Keyshelf © Light Straw Archive July 2012.

The Dugdale Exhibition
	Entitled "Number Please? working with the Enfield exchange.. The manual switchboard at Enfield exchange was in use from 22 July 1925 to 56 October 1960, when automatic switching took over." Photo: Three positions of the CB1, 'A position' Board which was on display, in the Dugdale Centre © Light Straw Archive July 2012.
At the Science Museum
	The Enfield CB1 is one of the permanent exhibits in the new 'Information Age' gallery, which was opened by Her Majesty the Queen on 24th October 2014. Photo: Enfield CB1 in the new gallery at the London Science Museum © LSA Oct 2014.

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