Things began disastrously for the visitors as their opponents hit the front early on, No. 8 Jack Digby taking a quick tap penalty five metres out before burrowing over for a try added to by Steffan James.
Park extended their advantage soon after, Rams failing to deal with a box kick before Luke Mehson raced in down the left.
The visitors rallied, however, and got on the board as Paddy Harris blasted over from close range, his maiden Rams score coming on his 57th appearance.
Mike Cooke added the extras, and his side were level at the end of the first quarter as Axel Kalling-Smith sent the outstanding Zach Clow clear, the full-back’s inside ball seeing Ollie Hodgson stopped just short before Oli Rhoads finished the job.
Rams grab lead but trail at break
And Rams then hit the front as Clow again scythed through, Rhoads furthering the attack before Rowan Grundy crossed, a brilliant conversion from Cooke making it 19-12.
Yet Park responded following a lengthy pause as their second row Jordan Martin was carried off, some slick handling ending with Benji Marfo over on the right.
The Londoners then regained the lead with the final play of a breathless first half, Rams winning a scrum against the head only for the ball to go loose – Mehson grabbing his second with a fine 50-metre finish.
The helter-skelter nature of a riveting contest continued as the visitors struck early in the second period, Connor Stapley picking off an interception before brilliantly streaking clear from inside his own half.
Clow brilliant in attack and defence
Cooke landed for 26-22, and the away side pulled further clear when Kalling-Smith – a real handful all afternoon – again went marauding forward before sending man-of-the-match Clow over for a deserved try.
The extras were again superbly added by Cooke, but Rosslyn fought back with plenty of possession and territory, only to be faced by a ferocious Rams rearguard, which saw Clow sensationally prevent Chris Preen from finishing what appeared a certain try.
The home side did eventually make it a one-score game again, though, George Orchard over from close range before James cut the gap to four points.
Yet with just two minutes remaining Rams made the decisive move, Kalling-Smith again at the heart of a move finished by debutant Henry Bartlett.
Cooke made it five from six, but there was still time for Park’s Joe Luca Smith to knock-on with the line at his mercy.
And following that warning shot, the visitors efficiently closed the contest out for a first win against a top-six side this term.
Rams head to Dings Crusaders for their final game of 2025 next Saturday (3pm).
