So church bells were once called (German glocke, French, cloche Mediæval Latin, cloca)
Wel sikerer [surer] was his crowyng in his logge Than is a clok [bell] or abbay orologge
Chaucer The Nonne Prestes Tale (1639-40)
The tale about St. Paul's clock striking thirteen is given in Walcott's Memorials of Westminster,
and refers to John Hatfield, who died 1770, aged 102. He was a soldier in the reign of William III, and was brought before a court-martial for falling asleep on duty upon Windsor Terrace. In proof of his innocence he asserted that he heard St. Paul's clock strike thirteen, which statement was confirmed by several witnesses.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894