Looking on Flashearth, nothing much to see of H.O.S.M now. I'm not sure when it closed, but I did hear that years ago the SATCO went to London for a medical and came back with a 'proximity' endorsement (meaning he couldn't work on his own, there had to be someone else present with the same ratings) and while he was away, most of the other controllers resigned to work at either Dishforth or Barkston Heath.