An early Luke Bouchier penalty gave the hosts the lead, but tries from Charlie Walker and Matt Woodward restored order for Park, Steffan James converting the latter.
Lions cut the gap before the break as Bouchier added to a Monty Loggenberg score, and a second penalty had them ahead going into the final quarter.
But Rosslyn took the spoils with James landing after maul tries from Cameron King and Max Fraine.
Plymouth, Sale push forward
Plymouth Albion climbed to third with a superb 50-26 success at Sedgley Park.
Ollie Glasse converted a Ben Gregory try to put Tigers in front, but the visitors responded as Harry Wilkinson and Shea Cornish dotted down, Iwan Jenkins adding to the first.
Sedgley regained the lead with a Josh Ree seven-pointer, but it was 24-14 at the break as Plymouth secured the try bonus thanks to Dan Pullinger and Ben Moa, Jenkins with another kick.
He added another after Archie Hill dotted down, but Park kept fighting and cut the gap to five points after Glasse slotted following a Billy Addy effort and Ree doubled up.
Albion, though, pulled away late on Jenkins adding two more conversions as Moa completed a hat-trick and Isaac Godfrey went over.
Sale leap-frogged Blackheath into fourth with a 26-21 home triumph.
The Dogs made it four wins on the spin despite falling behind to a Billy Harding try, added to by Matt Dalrymple.
Sale led 12-7 at the break as Evan Mintern and Corbin Thunder crossed, though, Joe Green on target for the second.
Mark Dixon’s seven-pointer extended the advantage before Club replied through Tom Johnson and Dalrymple.
The hosts effectively put the game to bed as Green converted Dan Birchall’s score, but Blackheath did salvage a losing bonus-point thanks to Tom Emery’s late try, Dalrymple again on target.
TJs bounce back, Stortford continue surge
Tonbridge Juddians complete the top half after snapping their two-match losing run with a 28-12 win at Clifton.
Victory also ended the hosts’ four-game winning streak, TJs taking control early as Connor Lloyd converted tries from Henry Paul and Tom Kendrick.
Clifton got on the board through Harry Hone, Ollie Millner with the extras, before Will Holling’s seven-pointer made it 21-7 at the interval.
Kendrick’s second sealed the bonus-point before Lloyd continued his perfect form from the tee, meaning an Ollie Harris try was merely a consolation for the hosts.
Bishop’s Stortford’s fourth straight win – a 33-26 home success versus Dings Crusaders – saw the Hertfordshire side up to ninth.
Yet it was the away team who led 12-0 early on, Sam Cantwell and Matt Jones touching down as Raff Weston converted the latter.
Stortford led at the break, though, David Hayes on target after Asa Stewart-Harris and Harry Clarke crossed.
Jake Morris extended the lead before Dings levelled, Alpha Ly over before Weston knocked over the kick.
Isaac Bell’s try was converted by Chris Bolton to put the hosts back in front, and Hayes did the same after Stewart-Harris doubled up for 33-19.
Dings, however, snaffled two late bonus-points as Weston added to a Sam Scott score.
Change of coach inspires Moseley at Leeds
New Birmingham Moseley head coach Ollie Thomas enjoyed the perfect start as his side ended a four-match losing run with a comprehensive 42-17 victory at Leeds Tykes.
The visitors raced into a 28-0 lead as Jack Jolly converted tries from Ben Pogson, Perry Humphreys, Ollie Stedman and Aquile Smith, Leeds on the board when Jerry Turagabeci added to an Alex Pleasants score.
But Jolly was again on target after Smith doubled up for 35-7 at the break.
Lucas Walsh went over midway through the final quarter for Tykes, Mose hitting back as Tighe Maxwell-Whiteley converted a Will Safe try.
Seb Krippner grabbed a late consolation for Leeds, but it was nowhere near enough for the Yorkshiremen.
Rams remain sixth after losing 35-31 to table-topping Rotherham Titans.
