The Quins qualified after a 29-15 win over Bridgend Sports Club in the second semi-final played in perfect conditions and led 19-0 at the interval.
They opened with a try by Adam Dawe after a good run by Mike Parfitt and Marc Sheppard converted. Then flanker Craig Cox went over and Steve Colarusso sent Marcus David in with Sheppard again goaling.
However, the Sports came back and winger Narberth crossed before outstanding forward Alan Lorimer followed twice in quick succession though all the conversion points were missed.
The Quins weathered the storm with Cox getting his second try and Australian replacement centre Tristrom Storm gained the final try.
