The visitors went ahead just after the half-hour when Rory McArdle rose highest in the box to power home Tom Kennedy’s corner to make it 1-0.
They doubled their lead just before the break when Will Buckley muscled his marker off the ball to fire home an angled drive into the far corner.
Brentford were never at the races in a lacklustre first half but came out all guns blazing after the break.
On-loan Ipswich striker Dean Bowditch gave the Bees hope when he converted Glenn Poole’s far-post cross with his head but the visitors held firm to claim three precious points.
The hosts were denied what looked like a blatant penalty when Kennedy appeared to handle in a goalmouth melee but the referee waved away the furious protests from Andy Scott’s side.