Determined defence and an ability to punish opponents’ errors carried Boroughmuir to victory in this basement battle.
Marr scored first, in nine minutes, MacKenzie Pearce driving over for a try, converted by Rory McGee.
Marr held their advantage until the 33rd minute, when Aubrey Mncube dived on a loose ball in the hosts’ in-goal area for a try, which Chris Laidlaw converted, before adding a 37th minute penalty to give the visitors an 8-7 half-time advantage.
Using the wind well, Marr kept their visitors pinned back in defence for most of the second half, but all they had to show for their complete territorial dominance was a 48th minute try by Glasgow Warrior Samuela Vunisa, surging over from a No.8 pick-up at a scrum.
However, in their first attack of the second half, from the restart, ’Muir regained the lead when a charged-down clearance kick fell into the arms of Archie Erskine, who stormed over, Laidlaw converting.
Erskine later crashed over for his second try, to make the victory safe.