Mary McKenna was the timid mother of police officer Alan McKenna, the fiancé of hairdresser Fiona Middleton. Initially all went well when Alan took Fiona home to meet his parents, but things soon went awry when Alan announced they were to get married in three weeks' time - while his parents were due to be away on holiday. Fiona refused to rearrange their forthcoming plans. After the fiasco at St. Luke's Church on the couple's wedding day, Mary was forced to act as go-between when Alan had a huge row with his father due to his bigoted comments about Fiona and her family.