I've researched the ancestry of LEG Oates (because of a similar rumour in my family that we were distantly related to him). I have found no connection with the Isle of Man (but did incidentally discover a connection to another branch of the Metcalf family, not related to my Oates or Metcalf lines).
Lawrence Edward Grace Oates was born in Putney, London, on 17 March, 1880. His parents were William Edward Oates and Caroline Annie Buckton. They were married in Leeds, Yorkshire in 1877. William Edward Oates, was born in Leeds, Yorkshire, in about 1841. Caroline Annie Buckton, was born in Kirkstall, Yorkshire in about 1853.