Pay on the nail - English phrase meaning to pay promptly
Bristol, England, was once a great financial centre and evidence of this is still in place today. The phrase 'to pay on the nail' is thought to have originated in here because deals were struck on brass 'nails'.
There are four Nails in Bristol, placed on the pavement outside The Corn Exchange. (@@N51:27:16 W2:35:40 @@)
They are brass pillars about 1m (3 feet) high with flat tops about 60cm (2 feet) in diameter (from memory - if anyone knows exactly please /msg me). They were made at different times in the 17th Century and bear Elizabethan and Jacobean inscriptions. One of them bears the name John Barker - a rich merchant who was Mayor of Bristol in 1623. The nails were moved to their current location when the Corn Exchange was completed in 1741.
Farmers would bring samples of their wares to Bristol to be sold on to merchants. A sample was placed on the top of the nail and a bargain would be struck. When the deal was agreed the merchant would place the money for the whole order on the nail and the farmer would be honour-bound to supply the goods. It seems that this is one step in advance of the meaning of the phrase today, in that the merchant was often paying in advance rather than just promptly, however the deal was made and the money paid on the nail.
Similar nails are to be found at the Limerick Stock Exchange and at the Liverpool Exchange. It is probable that portable nails have been used in markets and fairs in England since Anglo Saxon times.
According to Albert Herring this phrase is sometimes 'cash on the nail', but the meaning remains the same.