The name 'Tanner' for sixpence came from Victorian London

The Victorian nickname for a sixpence was a 'Thin' or, in rhyming slang a "Tanner and Skin", which became "Tanner".

As there have been mention of 'older' coinage, there used, over the years, to be four gold coins:
The Sovereign - £1 - 20 shillings - Known during the Napoleonic period, by some, as "Pitt's Cavalry" as it featured St George on the reverse and was used to hire/support foreign armies in the wars against France.
The Guinea - £1 1/- - 21 shillings
Half Guinea - 10/- - Ten shillings and six pence
Quarter Guinea -   5/3 - Five shillings and three pence - Recorded by Francis Grose as "The Whore's Curse"

Although Sovereigns are still minted, they effectively were taken out of circulation during the Great War.