TIM is 75 on Sunday 24th July

TIM is affectionate name for the BT speaking clock (or as it's now called Timeline), which was the first 3 letters of the T.I.M.E on the old telephone pad.

It's now accessed by dialling 123 and it still gets around 30m callers per year.

It was originally designed at the Post Office Engineering Research Station at Dollis Hill in North London (which is also where Collossus the code breaking 'computer' was conceived) and introduced on July 24th 1936. It was only available to London callers, only going national in 1942.

There have been 4 permanent voices the first being Jane Cain 1936 - 1963, followed by Pat Simmons 1963 – 1985 and Brian Cobby 1985 – 2007 (the only male voice) and finally Sara Mendes da Costa 2007 to present.

There have also been celebrity voices (Lenny Henry for Comic Relief in 2003 and Alicia Roland for ChildLine. Mae Whitman the voice of Tinker Bell in 2008 for the release of the movie and Gary Barlow, Cheryl Cole, Chris Moyles, Kimberley Walsh and Fearne Cotton for Comic Relief 2009).

The speaking clock used to be accurate to 1/10 of a sec on, but is now accurate to 5/1000's of a second (and Big Ben's time is checked against the speaking clock).