Because it was put in my head by @snathe and @fintanbear, here& #39;s a short thread of Post Office Telecommunications trimphones, starting in the Daily Mirror on 19 May 1977.

The Liverpool Echo, 15 October 1980

The Belfast Telegraph, 19 January 1970

A trimphone trimcrimewave in the Aberdeen Evening Express on 30 March 1976

And the pushbutton trimphone makes it debut in the Daily Mirror on 25 September 1978. If I& #39;m not mistaken, 01-246 8071 is the number for the recipe of the day (daytime) and the bedtime story (after 6pm).