Peter Derwent was a policeman and a friend of fellow officer Arthur Dewhurst, who had a short-term relationship with Elsie Tanner. The two had met when after Arthur had been beaten up by some criminals and left in the ginnel behind Coronation Street where Dennis Tanner had found him and brought him into No.11 to get cleaned up. He and Elsie started going out together, but the relationship was always faltering as the slow-talking older Arthur was neither love's young dream nor the sort of person that Elsie usually went out with. Moreover, she had met a far more suitable match in the person of rep Walter Fletcher at Miami Modes but nevertheless she persevered with Arthur as he had been the first one to take her out.
Arthur bought Peter into the Rovers on the night in June 1961 when Paul Cheveski, Elsie's grandson, was born and she was too distracted to pay Peter any special attention.
She grew tired of Arthur and his total lack of excitement and was trying to let him slip away from her life. Convinced she was seeing other men, Arthur brought Peter back into the Rovers, determined to have the matter out with her and seemingly wanting Peter there as moral support. He voiced his opinion that Arthur was lucky to have landed a "smart piece" like Elsie at his time of life, offending his friend by the back-handed compliment. When Elsie appeared in the pub, she fled into the snug to avoid Arthur and he appears to have realised that their time together was over, never seeing her again.