How does Pc Wetherby know Lesley?

Visitor Lesley Ashton arrives at the police house looking for Pc Don Wetherby, and as she talks to Pc Joe Mason about him, it transpires that she's an old flame. At the police station, married Don gets a shock when Lesley walks in, and quickly ushers her into a side room and tells her she must leave. That night, Nurse Carol is enjoying a romantic meal with new doctor Chris Oakley when Joe arrives with an injured Lesley. As Carol leaves Chris and Joe to stitch up Lesley's wound, it's clear there's hostilility between the two men. Is Joe hiding his true feelings for Carol? The next day, Lesley tells Sergeant Miller that she wants to make an official complaint about Don. Lesley tells Miller all about her relationship with Don and claims that he caused her injuries when he drove his car at her. With Joe as a witness to the incident, can Don clear his name and save his career? Also, Gina's struggling without Phil, and Oscar and Alf go undercover to investigate a spate of burglaries occurring while the occupants are staying at a nearby hotel.