A bizarre tradition involving a dead duck celebrated only once every 100 years is marked this weekend at an Oxford college.

On Sunday evening, Fellows of All Souls' will hunt for their mallard, who went missing almost 600 years ago.

According to the tradition, at the beginning of each century a Fellow of All Souls' known as Lord Mallard leads a procession through the college brandishing a duck on a stick.

This year, classics don Dr Martin West has been selected to be Lord Mallard. Judy Winchester, the college bursar's secretary, said it was planned to use a wooden replica mallard during this century's procession.

Mrs Winchester said: "It's one of those quirky Oxford things. They have done it every 100 years and they have decided to do it again this year."

Details of what happens at the event are scarce, but college records reveal the procession took place in 1901 and 1801.

The story of the mallard dates back to the 15th century. While builders were excavating the front quadrangle of the college in the 1440s a wild duck was spotted flying out of an old drain where it had been sheltering. Thereafter, the bird was adopted as the college's emblem.

Every 100 years since the, fellows have held festivities when they traditionally dine on wild duck and sing the Mallard Song, led by Lord Mallard.

In 1801, fellows of the college 'hunted' a live mallard, which was then tethered to a pole. They then drank its blood. One hundred years later, fellows considered this act to be barbaric and substituted a stuffed mallard for the live bird.

Historical documents suggest that during the 17th century the mallard emblem was associated with debauchery and revelry at the college.