The Reds gained a second successive five-point win, although they were made to work very hard by a determined home side before scoring a fourth try in the final play.
The visitors were into the attack early on and after their initial efforts were repelled, Tom Williams burst up the wing to score from 35 metres with eight minutes on the clock (pictured above).
An attritional period of play saw both sides unable to take their chances until a well-worked Ampthill move saw Will Foster cross in the corner and Louis Grimoldby add the extras to give his side the lead (5-7).
The Reds weren't behind for long, responding with a superb try that was made in Worcester, with loan signings Matti Williams and Scott Van Breda combing to devastating effect and the full-back haring to the line.
It seemed Williams (M) had scored a try of his own afterwards but the score was chalked off for a knock-on in the build-up, however the visitors were able to grab a third just before the break when prop Ciaran Parker followed a sprightly burst through the middle with a deft back-handed flick to Dan Barnes, who raced to the line from 15 metres out. Brendan Cope's second conversion made it 7-19 at the break.
The first score of the second period looked important and it was the hosts who grabbed it through wing Will Brown after 53 minutes with the wing racing through to a kick ahead (14-19).
With just the two exceptions, the Reds were consistently able to stymie most of the Ampthill attacking efforts and force errors, with the home side also responsible for the lions' share of the penalty count.
With just under 10 minutes to go there was a kickable penalty just outside the 22 and Cope took the shot to stretch his side's lead to eight points. And the Reds continued to press and eventually were able to work Barnes over for his second try, and the bonus point, with Cope adding the extra with the last kick of the day.
The result saw the Reds move up two places in the Greene King IPA Championship table, from ninth to seventh, just a point behind their hosts.
In other results, Cornish Pirates won 19-30 at Coventry, while Ealing Trailfinders were convincing winners over Richmond by 69-7. Saracens gained a big win at Nottingham in the late kick-off (0-56), with Sunday's action featuring a win for Doncaster Knights, who came from behind to eventually win by 27-19 at home to Bedford Blues.
Pictures: Claire Jeffrey
AMPTHILL (15-9; 1-8): Cameron Anderson; Will Brown, Josh Hallett, Richard Streets, Will Foster; Louis Grimoldby (capt), Matt Marsh (Sam Bryan 9); Sam Crean (Jamie Jack 58), Syd Blackmore (Dave Ward 35), Sam Wainwright (Aleki Lutui 53), Charlie Beckett (Carl Burgess 53), Llewelyn Jones, Billy Johnson, Jac Arthur (Alex Humfrey 48), Ollie Stonham.
Unused replacements: Russell Bennett, Jarryd Sage.
JERSEY REDS (15-9, 1-8): Scott Van Breda; Tom Williams (Darren Atkins 73), Jack Roberts, Dan Barnes, Brendan Owen; Brendan Cope, Max Green (James Elliott 72); Dan Richardson, Jack Macfarlane, Ciaran Parker (Jack Higgins 58), Sean O’Connor, Macauley Cook, Max Argyle, Lewis Wynne (capt), Matti Williams (Tim Grey, 32).
Unused replacements: Eoghan Clarke, Ollie Dawe, James Scott, Bader Pretorius.
REFEREE: Sara Cox. Assistants: Adam Wookey, Simon Adams
Half Time: 7-19
Official attendance: 0
Tries: Foster 22, Brown 53
Conversions: Grimoldby 22, 53
Tries: Williams T 8, Van Breda 24, Barnes 36, 80
Conversions: Cope 24, 36, 80
Penalty: Cope 70