Guernsey Raiders moved up to sixth place in National Three London as they leapfrogged Hertford with a 29-23 win.
The islanders were 15-12 down at half-time despite tries from Owen Thomas and Malcolm Barnes.
But Luke Sayer's excellent try after the break, running in from 20 yards, and a penalty try after a rolling maul gave Guernsey an 11-point lead.
Daniel Belton and Torran MacDougal crossed for the visitors but it was not enough as Guernsey hung on.
Guernsey are now three points behind third place as they prepare to face second-placed Tonbridge Juddian in their next match.