"John @ home" wrote

In preparation for decimalisation in 1971, London Transport moved all
fares to be multiples of 6d, which had an exact conversion at 2.5p.

British Rail did the same, one exception being platform tickets which were
4d, IIRC, before decimalisation, and became 2p on decimalisation. BR went
decimal a day earlier than the national D-day, so for the price of an Oxford
platform ticket (the last time I've ever bought one) I had in my hand the
change for a shilling of a 1p and a 2p coin a day before most people could
get hold of them.

Peter