The Sanctuary Knocker is an ornamental knocker on the door

Door knocker

A door knocker is an item of door furniture that allows people outside a house to alert those inside to their presence. A door knocker has a part fixed to the door, and a part which is attached to the door by a hinge, and may be lifted and used to strike a plate fitted to the door, or the door...

 of a cathedral

Cathedral

A cathedral is a Christian church that contains the seat of a bishop...

. Under medieval English common law

Common law

Common law is law developed by judges through decisions of courts and similar tribunals rather than through legislative statutes or executive branch action...

, these instruments supposedly afforded the right of asylum

Right of asylum

Right of asylum is an ancient juridical notion, under which a person persecuted for political opinions or religious beliefs in his or her own country may be protected by another sovereign authority, a foreign country, or church sanctuaries...

 to anybody who touched them. Examples of Sanctuary Knockers can be found on Durham Cathedral

Durham Cathedral

The Cathedral Church of Christ, Blessed Mary the Virgin and St Cuthbert of Durham is a cathedral in the city of Durham, England, the seat of the Anglican Bishop of Durham. The Bishopric dates from 995, with the present cathedral being founded in AD 1093...

, the St. Nicholas church

St Nicholas' Church, Gloucester

St Nicholas' Church, Gloucester, is a redundant Anglican church in Westgate Street in the city of Gloucester, England. It has been designated by English Heritage as a Grade I listed building, and is under the care of the Churches Conservation Trust. Its truncated spire is a landmark in the...

 in Gloucester

Gloucester

Gloucester is a city, district and county town of Gloucestershire in the South West region of England. Gloucester lies close to the Welsh border, and on the River Severn, approximately north-east of Bristol, and south-southwest of Birmingham....

 and the Church of the Holy Trinity, Stratford-upon-Avon. By 1623, the laws permitting church sanctuary had been overturned by parliament.