St Clements Danes were benefactors and many of their almshouses still remain in the city, http://www.bbc.co.uk/dna/h2g2/alabaster/A660269
Children would be taught the song so if they were to get lost in London they could just listen out for the bells and would know which direction home would be.
A vital practice in the days of the child snatcher, when children could easily wander off in the busy bustling streets and never be seen again.
There is a St Martin’s in the Fields at Trafalgar Square, the last time I was there was for Thanksgiving service with the Pearlie Kings and Queens, another great old London tradition. I always light a candle at St Martin’s in the fields when I can, for absent friends.