Hi topaz,Bow bells are in the city of London and not Bow in East London.Holborn,Covent Garden,St lukes Clerkenwell and Southwark,just over the river are the true Bow Bells areas.
The church is St Mary Le Bow,in Cheapside,although many people confuse it with the church in East London
Hope this does not cloud the issue,im just giving you this info in case your relative could be found in these areas.
Good luck.
Lawrence.