A pony is slang for a sum of 25 pounds, and not for an amount of 20 pounds. From the latter half of the eighteenth century, the word pony was used as slang for a sum of 25 pounds in the city of London, the capital of the United Kingdom.
Even though the exact origin of the term is not known, it is generally believed that the pony, slang for 25 pounds, is derived from the typical price one had to pay for a small horse. In those times, however, a sum of 25 pounds would have been an unusually high price for a pony.
Another suggestion was that an Indian banknote, which was worth 25 rupees, featured a pony. Another theory behind the origin of the word pony as slang for a sum of 25 pounds was that it was derived from the Latin phrase legem pone which meant the payment of a sum of money, cash down, etc.
Even though the exact origin of the term is not known, it is generally believed that the pony, slang for 25 pounds, is derived from the typical price one had to pay for a small horse. In those times, however, a sum of 25 pounds would have been an unusually high price for a pony.
Another suggestion was that an Indian banknote, which was worth 25 rupees, featured a pony. Another theory behind the origin of the word pony as slang for a sum of 25 pounds was that it was derived from the Latin phrase legem pone which meant the payment of a sum of money, cash down, etc.