Cole, 30, who worked as a consultant for Stroud Auction Rooms based near his family's home outside Dursley, had been travelling from Copenhagen to Assen to work with online auction site Catawiki.
Police say CCTV showed he was inebriated and had been robbed before he died.
Stroud's owners Lyn and Nick Bowkett, said: "We are in shock - although Richard was often off travelling, when he stepped back through the door, it was if he had never been away."
