The ancient shilling is history.

The so-called "one bob," a coin of the realm since 1504, ceased to be legal tender Tuesday and was replaced by a smaller 5-pence coin.The roughly quarter-size shillings - unchanged in size since 1816 - can be returned to banks for the next several months.

The government says it has retrieved 800 million shillings, leaving more than 4 billion still in circulation. The new 5-pence coin, about the size of a dime, is worth 91/2 cents at the current exchange rate.

The "bob" survived Britain's conversion to decimal coinage in February 1971, although new coins struck after that date were marked 5 new pence.

Old shillings remained in use, including some bearing the likeness of King George VI, the father of Queen Elizabeth II.

The Independent newspaper says the cost of converting coin machines will be between $57 million and $100 million.

In the old system, the shilling was worth 12 pence, or a 20th of a pound.

Old coins such as the sixpence or "tanner," and the "ha'penny," are only a memory.

The last of the old coins, the florin, worth two shillings or 10 pence, will be phased out in 1992, when new 1-pence and 2-pence coins will be introduced.

The shilling bowed out without anyone knowing why it was called a "bob," and leaving future generations never to know the comfort described in 1701 by poet John Philips:

"Happy the man who, void of care and strife,

"In silken or in leathern purse retains

"A splendid shilling."