Lateral thinking?

Nobby Stiles (don't you dare say "who's Nobby Stiles?"!) puts his World Cup medal up for auction.  It is bought by Manchester United - his old club - for £188,000-odd and will have pride of place in the club's museum.  So far, so good and a nice story, but what occurs to me is why didn't he offer it to the club privately in the first place?  I'm sure it is probably where he would have wished it to go, and that way both he and the club would have avoided having to pay commission to the auction house.  They're the ones coming out of this rubbing their hands!