Half-a-crown
From Tardis Wiki, the free Doctor Who reference
in Byzantium in 64, Ian Chesterton noted that none of the currency in use there resembled a half-a-crown or threepenny piece. (PROSE: Byzantium!)
A tea lady gave the Fifteenth Doctor and Ruby Sunday two cups of tea, and said they would cost half a crown. the Doctor and Ruby agreed that this was "outrageous", to which the lady responded "take it or leave it, sweetheart". (TV: The Devil's Chord)