The tower contains a peal of ten bells hung for English change ringing. They were cast at a number of different foundries and the heaviest, weighing 17 cwt, was cast in 1623. The bells are rung on many occasions during the year by the Oxford Society of Change Ringers at the invitation of the college. Such occasions include significant royal and college anniversaries, and after some services in the College Chapel. The bells received their last major overhaul in 2012, being returned to the tower in March of that year.