A dangerous prisoner was on the run last night after escaping from a lone prison officer who took him to a public house, unaware he was considered a high security risk. The officer escorting Richard Tyers to a drug rehabilitation hostel had been given a sealed envelope, to be opened only in the event of an escape. In it was a letter which said, “This man is an exceptional security risk. He has escaped in the past and is likely to try to escape again”.