There is a Gray family living in Kettins in 1901.  David and Jane Gray were living at Piteus Coachmans Cottage with their family, but there is no listing of a Martin there.  A Martin is on the CWGC site, son of Archibald Gray, of Longriggend, Lanarkshire, and husband of Elizabeth Yule Gray, of Blair Drummond, Perthshire.