Recorded as Trewin, Trewinnard and originally Trewennard, although this may well be an 'incorrect' spelling, this is a Cornish surname. It is locational from a place called Trewin or Trewinnard, the place name and hence the surname, translating as 'The White House'. Locational surnames throughout Europe were usually either names that were given to the original lord of the manor or his descendants, or to former inhabitants of the village who moved somewhere else. The easiest way to identify such 'strangers' being to call them by the name of the place from whence they came. However in Cornwall and in parts of the north of Scotland in particular, these 'rules' do not apply. For reasons unclear, in these areas people were called by the name of the place where they lived! Not surprisingly this lead to a very large identification problem, and resulted in the inhabiitants being identified by localised nicknames, such as 'Baker' Trewin or 'Butcher' Trewinnard or whatever. The surviving church registers perhaps not surprisingly, do not give the nicknames, and examples taken from them include Mrs Blaynch Trewennard of Constantine on February 26th 1626, when she married Thomas Elford, John Trewin of Breag, when he was a christening witness on January 1st 1656, and John Trewinnard of Mawnam Smith, on March 17th in the same year.