Durham Cathedral sanctuary was a lifeline to many a desperate man down the centuries. Far from being the quaint tradition we now see it as, sanctuary was a matter of life or death.
The story goes that to claim Durham Cathedral sanctuary, the criminal had to grab the big circular handle of the sanctuary knocker. Their pursuers then had to leave them alone, on pain of death.
The name of the fugitive would then be recorded in the Durham Cathedral sanctuary book. Between 1464 and 1525, 331 criminals claimed Durham Cathedral sanctuary, including 283 murderers. There was clearly a bit of a trend among the homicidal.
You'll find historical stories of sanctuary surrounding many cathedrals and churches. A large ringed knocker is the usual giveaway - a nice easy handhold to aim for when being chased. It also eliminated any ambiguity of what constituted sanctuary. No question of touching the cathedral or whether the fugitive had to be inside: everyone knew that once the fleeing person had grabbed the knocker handle, they were safe - at least, relatively and temporarily.
The story may have been embellished a little, however. The imagery of a desperate figure fleeing from a pursuing party hot on their heels, and making a grab for the ring to claim Durham Cathedral sanctuary just in time may be a compelling thought, but the truth was probably a little more mundane. The pursuits were probably not so close run and the right of sanctuary most likely extended far beyond Durham Cathedral itself, possibly even to the Durham boundaries of Gilesgate and Neville's Cross.
However, one thing is clear: Durham Cathedral sanctuary was a rule by which everyone abided. Failure to do so could lead to death, or at the very least excommunication. The concept of sanctuary in Britain began in 597AD; more specifically in the case of Durham Cathedral sanctuary, Saxon laws gave these powers to St Cuthbert's Community in around 900AD. Subsequent generations of rulers and dynasties allowed the law to continue, and it was still possible to claim Durham Cathedral sanctuary as late as 1623.
Once a fugitive had claimed sanctuary, they had 37 days to get their affairs in order, then choose either to walk out and stand trial, or to accept their guilt and be banished from the realm.