With decimalisation, the pound kept its old value and name, and the only changes were in relation to the subunits. The shilling was abolished, and the pound was subdivided into 100 "new pence" (abbreviated "p"), each of which was worth 2.4 "old pence" (abbreviated "d").

Why did shillings have 12 pennies?

1 shilling equalled twelve pence (12d). There were 240 pennies to a pound because originally 240 silver penny coins weighed 1 pound (1lb). ... An amount such as 12/6 would be pronounced 'twelve and six' as a more casual form of 'twelve shillings and sixpence'.

How did pre-decimal money work?

For the majority of English (and eventually British) history, a pre-decimal monetary system based on pounds, shillings and pence was used. In this pre-decimal currency, one pound sterling was divided into twenty shillings, and one shilling into 12 pence. This meant there were 240 pennies to the pound.