Midlothian were undefeated at home but Bainfield battered them, achieving a lead of 25 after 11 ends.
Wins by the rinks skipped by Mike Marshall and Jim Cowan were ably supported by a strong finishing Tam Seggie to salvage a peel leaving Adam Brock the only loser for the visitors.
The defeat is a setback to Midlothian as they are now four points adrift of the joint leaders and Frank Gray said: “I can’t hide the fact that my own rink was on the end of a good hiding.”
East Lothian, meanwhile, thrashed rivals West Lothian 79-39 at home, but Portobello were thumped 78-44 by fellow strugglers Tweedbank at Galashiels. Teviotdale opened their account at the seventh time of asking with a 67-55 victory at home to Bathgate club Balbardie.