When did the pounds and pence replace the shillings?

In Britain, 15th February 1971. This was known as Decimalisation day.

The currency change from £sd to £p.

Prior to 15/2/1971: 1 Shilling = 12d (pence); £1 = 20 Shillings = 240d.

After this, £1 = 100p ('new pence', but the 'new' was later dropped).

Ireland decimalised on the same day (15th February 1971)

Australia decimalised on 14th February 1966, but in this case the pound (£) was replaced by a dollar worth 10 Shillings.