What Is The Most Unusual Custom/tradition In The British Isles?

There are lots of these, but one of the oddest is the Shapwick Monster celebration.

Shapwick is a small, quite isolated village in north Dorset (a south-western county of England.) In the 19th century there was great excitement in Shapwick (usually pronounced SHAPPICK) when some local people said they had found a monster lying in the road.

Everyone gathered to look at the "monster" and nobody could guess what it might be. Finally someone managed to identify the strange beast - it was in fact a very large crab, which had been brought into the village on a fishmonger's cart, and accidentally dropped.

This story gives us some insight into how isolated village life could be before modern transport - Dorset is a coastal county and nowadays you would drive from Shapwick to the seaside in a short time, but hardly anyone from the village had ever seen the sea, let alone a crab.

The incident left such a mark that even today, on the anniversary of that day, the people hold a procesion through the village streets, carrying a large stuffed crab.