Update: Mr Tomlison has now been found
Stephen, who is from Darlington, was last seen at around 11pm at the Black Horse pub by his friends.
It appears that Stephen did not return to the hotel where he was staying, and his friends raised the alarm this afternoon after he failed to get in touch with them.
Officers are carrying out searches and conducting enquiries to help find Stephen and are appealing to anyone who may have seen since 11pm last night, or knows where he is now, to contact them.
Stephen is described as white, with a pink complexion and fair hair. He was last seen wearing navy blue shorts, a light blue short-sleeved shirt and black shoes.
Anyone with any information is asked to contact North Yorkshire Police on 101 and pass information to the Force Control Room.
Please quote reference number 271 of 18 June.