According to oral tradition recorded by Enid Porter in Cambridgeshire Customs and Folklore (1969), there is a subterranean passage that runs as far as King’s College chapel. It was said to be a safe route for members of the college to escape from Cambridge in times of plague.
As with most subterranean passage traditions, the length of the tunnel is probably exaggerated, though it may indeed have had an ecclesiastical connection. Some years before Enid Porter was writing, it was explored for four or five yards (4m) and appeared to lead under the lawn towards Grantchester church.
Another tradition is hinted at in a seventeenth-century map of the village. One of the fields is named ‘Fiddler’s Close’. This might refer to a landowner, or the use of the field for Morris dancing, but it might also preserve the story told by Enid Porter: ‘The Lost Fiddler of Grantchester’.
This says that a fiddler once announced his intention of exploring the tunnel to see how far it led. Bravely playing his fiddle, he set out, his music at first sounding loud and clear. Then it gradually grew fainter until it could be heard no longer. The fiddler himself was never seen again.
(Note: Similar stories are told of Anstey Cave Gate, Hertfordshire, and Binham Priory, Norfolk.)