It's the Malankara Mar Thoma Syrian Church, often shortened to Mar Thoma Church:
Reformed Oriental church based in Kerala, India. While continuing many of the Syriac high church practices, the church is reformed in its theology and doctrines. It employs a reformed variant of the West Syriac Rite Divine Liturgy of Saint James, translated to Malayalam.[
It surprised me to find it on a random street in Bedminster, but I don't know much about religion, or Bristol's Syrian community, assuming that that might be the flock, in general?
GPS Coordinates:
51.44334, -2.60501
Location: Southville