Dotty you are correct. Ida Barlow, played by Noel Dyson, was run over and killed by a bus, although it was never shown, merely referred to. She was the first regular character to be 'killed off'. This was because her family commitments were in London and she did not want to be tied down to long contractual hours in Manchester so she declined to renew her contract. She was often seen in cameo roles in TV series after that and died in 1995. Funnily enough she played Arthur Lowe's wife in the sitcom Potter, which ran for four years.