Sean Regan was the Irish second husband of Concepta Hewitt. Sean met Concepta when he answered her advert for a foreman at the family garage, which she was struggling to manage on her own. Love blossomed and by October 1972 they were engaged. Some months before they got wed, Sean and Concepta travelled from their home in Ireland to Weatherfield. Concepta's old friends gave them a warm welcome but Lucille Hewitt, Concepta's stepdaughter from her marriage to Harry Hewitt, took a while to be convinced that they were marrying for the right reasons.
Sean and Concepta were invited to stay at the Rovers by Annie Walker, Concepta's friend and former employer. While there, Sean kept making passes at barmaid Bet Lynch, but worried about upsetting Concepta or Annie she kept quiet about it.
Three years later, in November 1975, Sean had a short stay in Weatherfield and again was a guest at the Rovers. With Concepta away, Bet had a difficult time fighting off Sean's constant advances. Sean plotted to have Bet to himself and sabotaged a planned evening between Bet and her boyfriend Frank Bradley so they could be alone together. As Bet had already made her feelings clear, she at first pretended to enjoy having his attentions and then hit him, telling him she was going to write to Concepta and tell her what a rat she'd married. Sean walked out of the Rovers and didn't return to the Street, although the incident nearly cost Bet her job as she had to explain Sean's sudden departure to Annie, who accused her of trying to lead a happily married man astray. When Len Fairclough backed up Bet's account of the kind of man Sean really was, Annie was apologetic and convinced Bet not to send the letter to Concepta. To Annie's surprise, when Concepta visited Weatherfield for the New Year, Concepta admitted to her that she knew that Sean slept around but as he was still a good husband to her and stepfather to Lucille and Christopher, she put up with him.