The shilling, also known as a bob, (AUDIO: The Vardan Invasion of Mirth) was a unit of currency used in the United Kingdom up to the mid 20th century.
There were twelve pennies in a shilling and twenty shillings in a pound, meaning that there were 240 pennies in a pound. (TV: Remembrance of the Daleks)
Entry to the Great Exhibition for one visitor cost 1 shilling. The Eighth Doctor earned 12 pennies for his ticket by performing a trick 12 times. (AUDIO: Other Lives)
In 1953, John Ellis charged his son Alan Ellis' friends a shilling each to watch the FA Cup final between Blackpool F.C. and Bolton Wanderers on his new television. (TV: Out of Time)
Susan Foreman, being a time traveller, had visited Britain's future prior to her arrival in 1963. Confused, she could not remember how many shillings were in a pound when she and the First Doctor settled down in London in that time. She thought that they had already decimalised the currency, to the amusement of the other students at Coal Hill School. (TV: An Unearthly Child)
In 1998, Helen Sinclair asked a taxi driver what "2.50" was in shillings, not being familiar with the decimal system. (AUDIO: Absent Friends)
The currency was still used during the far future. When Hame was very young, her parents sold her to the Sisters of Plenitude for 10 shillings, so that they could afford taking themselves and Hame's siblings out of Restitution. (WC: The Secret of Novice Hame)
Behind the scenes
Interestingly, with An Unearthly Child set and broadcast in 1963, Susan accurately predicts that the United Kingdom would switch to decimal currency, which in the real world was announced in 1966 and occurred in 1971.