The Edinburgh fireman blazed a 7-0 opening trail against his 43-year-old opponent, but the city cab driver engaged a higher gear to accelerate to nine before Donaldson hit back with a run of 4, 1, 1 to regain the upper-hand at 13-9.
It was all square at 14-14 after 14-ends and all to play for, but Cockburn run out of petrol, causing the three times champion to crash to defeat as Donaldson powered to 21 with a 3, 1, 1, 2 finish.
“I am thrilled to bits at winning this one as I was under great pressure at home to emulate the championship success of my mum Moira ,who recently beat Joan Gracie 21-18 to retain the ladies title at Parkside”.
Donaldson was etching his name on the trophy of the club for the third time in four years and the two previous occasions saw him go on to the reach the final of the E&L Tait Trophy in 2009 then win it in 2010.
Meanwhile, last night’s climax to the club championship at Postal saw 25-year-old Neal Rooney capture the title for a second time, and in grand style as he scored a commanding 21-12 win over holder Christain Berra (62)
Rooney added 4, 1, 1 to make telling space to 10-3 then enjoyed a second purple patch spell from 10-7 to 18-8.