Douglas lost 13-9 on the road at an uncompromising Trentham who took advantage of some indifferent refereeing in the South Lancashire/Cheshire Division Two encounter.
Trentham led 7-6 at half-time, with two penalties from Douglas kicking maestro Bryn Snellgrove keeping his side in the hunt.
A further penalty from Snellgrove in the second half gave Douglas a sniff of a win, however, when Laurie Williams and his opposite number were both sin binned, Trentham cashed in quickly and two further penalties gave them the points.
David Mullarkey selected by Great Britain for road running championships
Harris wins opening qualifying round at US Open
Michael Dunlop wins Senior Classic TT
Johnny Stewart wins Senior Manx Grand Prix