By Melissa Jones Early Scottish Grand National mishaps for Willie Mullins were quickly forgotten as Macdermott delivered a thrilling victory. The 18-1 market drifter just held on from Surrey Quest in a photo finish to scoop £112,540 for his Irish trainer and connections. Macdermott’s nose success gives Mullins, who celebrated a stunning 4,462-1 four-timer at Ayr, a huge advantage in the British trainers’ championship with a week to go. But the ending of the four-mile race was in stark contrast to its beginning when Mr Incredible, his shortest-priced contender at 7-1, pulled himself up before t…