A bright start to the game from the Dees team saw S&L give away a penalty just outside their own 22m with only seven minutes on the clock.
The trusty boot of Kevin Boland was on hand to convert the kick and give Dunstablians an early 3-0 lead.
From the restart, S&L fought to get back into the game but the brutal defence by the Dees back row of Nathan Dominique, Ashley Warren and skipper Aaron White refused to give way.
A thumping tackle from Dominique stopped his opponent and team-mate Lukas Chamberlain, who although attempting to battle on, had to leave the field with a broken thumb.
Although Dees held their lead at the interval, two penalties gave S&L the opportunity to kick for the corner early in the second half.
Both times they managed to drive over the line to score, with one conversion putting them 12-3 in front.
These two attacks were the sum total of S&L’s limited visits to the Dees line as the hosts’ defensce stayed strong, with prop William Hewitt making a number of big tackles.
However, it was the lack of consistency at the lineout that weighed Dees down, while they failed to finish off a number of attacking moves, letting the opportunity of a major league upset get away from them.
Dees, in sixth, host seventh-placed Leicester Forest this weekend.