Changing the coins could be justified as keeping them relevant for the future, otherwise they become irrelevant through inflation. When ½p coins were introduce

Changing the coins could be justified as keeping them relevant for the future, otherwise they become irrelevant through inflation. When ½p coins were introduced with decimalization, a pint of milk cost 5p — the smallest coin bought 57ml of milk. With milk now 90p/pt, you now get only 6ml for the smallest coin. We could reasonably scrap 1p, 2p and 5p coins.