in 1978, williamson moved to the diocese of london. he served as a curate at |holy trinity with st mary, hoxton from 1978 to 1983, at all saints, margaret street from 1983 to 1984, and at st mary's, willesden from 1984 to 1985. for the next three years, he was not attached to any parish but held permission to officiate in the diocese. in 1989, he joined st george's church, hanworth as a curate. since 1992, he has been priest-in-charge of st george's.