With only pride to play for in this match, Cinderford recovered from a 7-24 deficit after half an hours play to score 40 unanswered points and wrap their season with a bonus point victory.
Dewi Scourfield scored an early try for the home side but Cambridge hit back when Albert Portsmouth kicked a penalty and then converted a try from No8 Steve Hipwell.
The visitors then took advantage of some slack play from their opponents to score further tries from Portsmouth and Mike Gillick, both of which were converted by Portsmouth.
A yellow card shown to Cambridge second-row Bryn Jenkins saw Cinderford take advantage of the extra man when winger Lloyd Stapleton crossed for an unconverted try just before half-time.
With the wind at their backs in the second-half Cinderford were quickly on the offensive and after a sustained period of pressure No8 Joe Garner went over for a try from a scrum 5m out, with Davies converting.
The home side went back in front when Rob Langley forced his over, with Davies on target with the conversion.
After this Cinderford cut loose with further tries from Nev Codlin, a second from Garner and replacement prop Chris Bundy, all of which were converted by Davies.
Said director of rugby Andy Deacon: “We are pleased to have finished the season with a win at home with several indifferent results recently. In the second half we delivered a great performance that takes us into next season finishing on a high.”
Man of the match – Dale Critchley, Cinderford
Stef Hawley, Nev Codlin, Jack Adams (Mike Wilcox 70), Dewi Scourfield, Lloyd Stapleton, Mark Davies, Alex Frame (Danny Pointon 50), Joe Smart (Chris Bundy 67), Tom Bozzard (Stu Bailey 60), Nick Selway, Ben West, Dale Critchley, Rob Langley, Will Foden, Joe Garner (George Evans 67)