Just looking at 1939. There was a Henry McKinley, no middle name listed, labourer, death in Mullingar, Westmeath in 1939, but it was signed by someone from the hospital he was in at time, so not obvious if it could have been Henry Hugh McKinley.
However, what makes it more of a possibility, perhaps, is that a Henry Hugh McKinley married a Mary Costello in Mullingar in 1942 (a number of children then born to them in the area). Perhaps the same Henry Hugh McKinley born in 1913.