Shady Old Lady tells us that there was originally a cottage on the site where a widow lived, with her only son, a sailor. He was apparently due to return home on Good Friday 1824 and asked his mother to bake him some hot cross buns.
Her son never returned, but every Good Friday the mother continued to bake for him and had a new bun waiting. Each year a new bun was hung from a beam in her cottage, and when she died they were found there. It became known as the Bun House.
In 1848 the cottage was replaced by a pub but the successive landlords have kept the tradition alive. Each year a member of the Royal Navy is invited to place a freshly baked hot cross bun in a net above the bar. Your author understands the traditional hanging of the bun takes place roughly between two and three o'clock this afternoon at the Widow's Son, Devons Rd, E3 3PJ. For more, see here