Stirling opened the scoring against the run of play when Ratu Tagive scampered in at the corner. Andrew Goudie missed the conversion and a penalty in the 16th minute but made amends shortly afterwards when he nudged over a kick to stretch the lead.
Lee Millar reduced the leeway with a simple kick after 28 minutes but it was mostly Stirling on top despite a regularly misfiring lineout.
Watsonians were curiously out of sorts in the first half but Millar added to his tally soon after the interval with a long-range kick.
Ewan Fox then sprinted over the line in the right corner to give his team the lead for the first time, and though Millar’s conversion attempt come back off the upright, he was on target with a little over ten minutes left on the clock for a six-point advantage that was to prove enough in the end.