> Important to remember that it was really only the value of pennies that was altered.
>
> There were (and still are) twenty shillings to the pound (and for those of you who attend horse sales or art auctions - 21 shillings to the guinea)
>
> At decimilisation, the shilling was made up of 5 new pence instead of 12 pennies

Not quite true. After decimalisation, the shilling ceased to exist, as a formal unit of currency. However, as the shilling coin was still legal tender, and still worth 1/20 pound, people continued to use the term on an informal basis. The florin (two-shilling coin) also remained legal tender as the new 10p coin, and is has been legal tender for longer than any other coin in the world - from 1344 until 1992.

To correct a further minor error: The plural "pennies" applies specifically to 1 penny coins. As a value of money, the correct plural is "pence", thus your final sentence should have been "...5 new pence instead of 12 pence". If you want to disambiguate the difference between pre- and post-decimalisation currencies, then "12 old pence" would be more correct than "12 pennies".

wintermute