This was first published by Anne Furlong on her blog Unexpected Nomad. The church is St. Mark’s in London. If you’re familiar with Prince’s slave narrative, you might remember her mentioning the Rev. Mr. Mortimer, “the good clergyman of the parish, under whose ministry I have now sat for upwards of twelve months” (Ferguson 92). St. Mark’s was his charge.
Originally posted on UnexpectedNomad:
I came to this church with a friend who is tracing the steps of Mary Prince: born into slavery in Bermuda, brought to the UK on a soon-broken promise of manumission, she left her captivity under the narrow shadow of the law. 
The Moravians offered refuge, and Thomas Pringle, connected with this place, gave her the work that led to her autobiography. Pringle had failed to make a living as a writer, a teacher, and a publisher in Scotland and South Africa.
In London, the Anti-Slavery Society engaged him as Secretary, a position he filled for seven years, until his death. Think of it. The African Caribbean woman in drab, dirty London, and the Scot from bright, hot Cape Town. They met here, in the new built church, and changed the world.