No source for this statement has been found. But it seems possible that 1542 is a misprint of 1562, when Huguenots desecrated the tomb of William I in the abbey church of St Etienne in Caen and brought his physical remains to light - C. Hippeau, L'Abbaye de Saint-Etienne de Caen (Caen, 1855), 181-2 (quoting an eye-witness account).