DARRAGH Fanning’s opportunistic try ten minutes from the end saw Leinster A maintain their winning start to their British & Irish Cup defence.
With his side trailing 22-17 the St Mary's winger finished off a break by John Cooney which gave Cathal Marsh the conversion to continue his side's perfect start to Pool One.
The kick sailed over and Leinster were rewarded for withstanding a first half onslaught, taking their chances after the break and hitting the front at the perfect time.
Indeed Marsh's conversion, his fourth success from four attempts, was the only time Leinster led throughout the entire match.
Girvan Dempsey's men would have felt pleased with their first half efforts, despite trailing 12-7 at the midway point they had played into a strong wind and up the Billesley slope.
Indeed Thomas Daly almost opened the scoring in the fourth minute after an incisive 30m break by Cathal Marsh.
The fly half was scragged into the 22 by Mike Penn but with Conor Gilsenan in support the ball reached Daly only for the centre to be bundled into touch.
Buoyed by that let off Moseley went down the slope and Ollie Thomas kicked a seventh minute penalty following a ruck infringement by Thomas Denton.
The home full back doubled the lead sooner after his forwards rumbled up to the 22 and won another penalty for a high tackle.
Almost immediately Gilsenan was sin-binned for a late hit on Thomas as he chipped over halfway but was taken out by the openside.
Thomas picked himself up and stroked a 50m penalty clean through the sticks.
And he made it 12-0 just after the midway point when the Birmingham outfit's scrum forced Leinster's seven men to stand up.
Gilsenan returned to the fray and Leinster were handed an attacking opportunity when Moseley messed up a lineout maul and were accidentally offside.
From the resulting scrum Leo Auva'a quick a quick tap and thundered through flimsy defence. Marsh converted to cut the deficit to five-points.
Leinster had use of the elements after the turnaround, although they were given what seemed a mountain to climb when four minutes after the restart Thomas scored Moseley's only try.
Will Hooley reversed play against the grain inviting Thomas to glide into the line, through the defence to touch down from 20m. His conversion made it 19-7.
A quarter of an hour into the second period the visitors came back into it after opting to maul a kickable penalty.
The lineout drive was held but Sam Coughlan-Murray was off his wing to take Marsh's shortened pass 15m to the line. Marsh converted.
Another Thomas penalty gave his side an eight-point advantage just before the hour, which was reduced again by three points from Marsh's boot.
Then in the 69th minute Cooney burst up the side of a maul in his own 22, kicked behind the defence and Fanning scooped up the loose ball, shrugged off a couple of tackles and rumbled over. Marsh completed the job.