And to emphasize a point in the report: FIRST the SAA caught the Brits THEN they launched an operation in E. Ghouta:
Syrian Army Captures British
I sense a little propagandizing by Hezbollah and/or Iran's military in some of the details of the plot, but the basic story is plausible. It would be even more plausible if the Syrian government produced those British troops for the public to see. However, the government could be looking at the troops as a bargaining chip, so to speak.
Here is the FARS report that Sputnik referenced.