Earlier this week, with what was once the world’s greatest race mere days away, Horse Racing Ireland commissioned some filming at the Curragh yard of trainer Martin Brassil. Brassil was not the star of the feature; nor was former jockey Niall ‘Slippers’ Madden. The centre of focus and love was the 30-year-old thoroughbred Numbersixvalverde two decades on from his win in the Aintree Grand National. He was Brassil’s first runner in the four-and-a-quarter-mile extravaganza. It was Madden’s first ride in a race that for so long made four nations forget their troubles, if even for a few minutes – or…