The nursery rhyme has nothing to do with Cambridge but refers to churches in and around the City of London.
St Clement’s is usually assumed to be St Clement Danes (10 bells) in the Strand, the RAF church, but may be St Clement Eastcheap. Both are riverside churches near where citrus fruits were landed, but there is no record of the Eastcheap church having a ring of bells.
St Martin’s is associated with St Martin-in-the-Fields (12 bells) in Trafalgar Square, but could be St Martin Orgar in the city, although that church has not had a ring of bells since the Great Fire in 1666.
St Sepulchre-without-Newgate (12 bells) is opposite the Old Bailey and near the site of the Fleet debtors prison.
Shoreditch, just outside the city walls was a notably poor area. St Leonard’s, Shoreditch is however a fine church with 12 bells.
St Dunstan’s, Stepney (10 bells) is also outside the city walls on a site dating from the 10th Century.
St Mary-le-Bow (12 bells) is in the centre of the city, and traditionally a true cockney had to be born within the sound of Bow Bells. It has a heavy ring of 12 bells which replaced an earlier ring destroyed in the Blitz. A recording of the old bells used to be played regularly by the BBC during the Second World War.
All these rings of bells are in regular use and can be rung by those with the necessary skill. Learning to ring provides the opportunity to ring change-ringing bells around the world. Many ringers enjoy adding to the list of churches where they have rung - a few have collected thousands.