The Reds head coach was delighted with the performance, as tries from captain Colin Stuart and full-back James Ferguson helped the Reds to a crucial victory in their push for promotion.
Thomas said post-match: “I thought the players were outstanding throughout the match.
“In very challenging conditions, they showed huge commitment and team spirit to overcome a Dumfries side who had only lost twice this season.”
The commitment was led by the Reds pack, who gained the upper hand on their opponents at the set-piece, Garry Cockburn and prop Alan Laidlaw dominant once more alongside skipper Stuart.
In difficult conditions, neither side was able to put together a sustained period of pressure, until the Reds took the lead just before the half-hour.
The pack won good ball, which was worked through the hands of the three-quarters, where Kyle Adams broke the line, and he fed the ball inside tof ull-back Ferguson away to score his third try of the season.
Gareth Pritchard missed the difficult conversion, but the Reds led 5-0.
The game’s opening try seemed to shock the visitors, who put together their best spell of the half before the interval, and were rewarded with a try of their own.
Again the conversion was missed, and the two sides turned round level at the break, 5-5.
The Reds got off to the perfect start to the second half when skipper Stuart latched on to the back of a maul and powered his way over the line.
A try to start a week of celebrations for the club captain, who celebrated his birthday earlier this week.
Pritchard landed the conversion and the hosts led 12-5.
And despite there being more than half an hour left, the Reds held on to record a memorable victory in testing conditions.
The 1st XV return to action at Neilson Park on Saturday as they take on East Kilbride, while the 2nds are on the road at Dalkeith.

Haddington: James Ferguson, Kyle Adams, Kyle Hamilton, Liam Clutton, Ian Watt; Gareth Pritchard, Jack Hamilton; Alan Laidlaw, Colin Stuart CAPTAIN, Garry Cockburn, Ben Laing, Charlie Hamilton, Kyle McGarvie, Kris Paterson, Mark Renton.
Replacements: Alex Cunningham, Jonny Riddell, Harry Hamilton and Mark Robertson