IMAGINE the scene. You're walking down Worcester High Street one fine May morning when a total stranger starts whipping you with a bunch of stinging nettles and then gives your bottom a good pinch, too.

Most people would be a little annoyed by such outrageous behaviour. Nevertheless, there was a time when this could have been your fate if you'd been caught not wearing oak leaves on a certain day in late spring.

Most people are aware of the pivotal role played by the Faithful City during the English Civil Wars. However, a tradition associated with that period of history is lesser known and was fast fading into the mists of time until along came a young Worcester historian by the name of Paul Harding.

He has vowed to revive Oak Apple Day, a celebration that was - until the 1990s - faithfully observed in Worcester, particularly at the Guildhall. And to emphasise the point, his organisation - Discover History - aims to be out in force on Tuesday, May 29, to press for a revival of this ancient custom.

The events are fairly well known. The future Charles II brought an army of about 12,000 men to Worcester in August, 1651, after marching 300 miles in just three weeks from Scotland. Facing him was the New Model Army commanded by Oliver Cromwell.

The battle of Worcester began on September 3, and as nightfall began, the king's forces were in full retreat along Worcester's winding streets. The king fled his lodgings in the Cornmarket and began his famous six-week escape to France.

He disguised himself variously as a maid and a woodcutter. On September 6, Parliament put up a £1,000 reward for his capture.

Charles and one of his loyal officers, William Carlis, were forced to leave their hideout and sit in the branches of a large oak tree near Boscobel House in Staffordshire. Meanwhile, Parliamentary soldiers swarmed about below. Paul takes up the story "Charles reached France and eventually went to live in exile in Holland while a commonwealth ruled England. When Oliver Cromwell died in 1658, his son took over.

"However, a number of powerful figures argued about his ability to govern. Soon, old soldiers such as General George Monck decided to act.

It was at this time that the restoration of the monarchy was called for. After some opposition, a letter was sent to the exiled king and Charles was invited home. "Charles entered London with great ceremony on May 29, 1660 - his birthday. This date was then designated a day of celebration and given the name Oak Apple Day in honour of the tree that had protected the king. An act of Parliament fixed it in 1664," he said.

Once again, the land was swept by change. Old Puritan ways were abolished, and banned events - such as celebrating Christmas - reinstated. Charles became known as the Merry Monarch. However, there was a darker side to this counter-revolution. Eleven members of Parliament were hanged, drawn and quartered because their names were found on the death warrant of Charles I. The corpse of Oliver Cromwell was dug up and also suffered the same fate. Nevertheless, General Monck was pardoned, as were other veterans of the Parliamentary Army.

"Oak Apple Day was celebrated in Britain on a grand scale until 1859 when it ceased to be a public holiday," said Paul. "It still survives at the Royal Hospital Chelsea, which was founded by Charles II. Celebrating Oak Apple Day is often taken in the form of wearing oak leaves. It was once a common punishment to whip a person with stinging nettles for not wearing oak leaves or pinch them. This is why the day was sometimes called Nettle or Pinch Bum Day.

"The original oak was killed off by trophy hunters in the 1700s and a descendant of the tree was also felled following the great storm of 1987. Today, a tree still stands, and is said to be directly descended from the original Royal Oak."

Worcester once celebrated the day by covering the gates of the Guildhall with oak leaves and often used local re-enactment group the Worcester Militia. However, since the late 1990s, the tradition went into decline, and for the past few years, the Guildhall has not been decorated.

Paul said: "Discover History wants to revive this custom - it is a shame how traditions are forgotten. The king made his escape from Worcester in 1651 and we think Oak Apple Day should still be celebrated. The restoration is a significant part of our heritage."