Centre Dan Barnes scored late to hand the Islanders maximum points in Bedfordshire, having collected the full five points a week earlier in a club-record victory at home to Nottingham.
Tom Williams opened the scoring with a dash up the wing inside ten minutes, before the hosts took the lead through a Will Foster try and Louis Grimoldby conversion.
However, Worcester loan signings Matti Williams and Scott Van Breda linked up superbly to release the latter for Jersey’s second, before prop Ciaran Parker unleashed Barnes for his first – and a 19-7 half-time lead – with a nifty flick.
Ampthill reduced the arrears after the break through Will Brown, but Brendan Cope then split the posts with a penalty and Barnes was worked over to seal a third win in seven games.
