of April 1261, Walter and Mary were ruling the province as Count and Countess.

The Countess Mary predeceased her husband, probably before 1286. Their tombstone is preserved in the Priory of Inchmahome, bearing the effigies of husband and wife, the former bearing on his shield the Stewart fess chequy with a label of five points, a device which also appears on his seal of arms in the Public Record Office, London.