what king Gregory ? - the most famous link was Pope Gregory whose papal bull re Island still survives see http://www.ee.surrey.ac.uk/Contrib/manx/jmmuseum/d175.htm

the name Gregory occurs seldom and always as far as I can tell always in conjunction with a non manx eg Gregory Andrew was a soldier in 1660's but Andrew (like Cambell) is not a 'classic' manx family name