season 3 ending didn't make sense

I discovered this show only recently and have watched through series three. If I remember correctly...

I think the connection we're supposed to make is that Leanne/Lena saw Asha meeting Michael in the hotel in Glasgow where she was a chambermaid. Lena remembered Asha from the situation with her mother and figured out that Michael was in the witness protection program. She followed him onto the ferry in hopes that Asha would follow, but that didn't happen. She saw the tussle between Robbie and Michael and afterwards learned who Michael was from Robbie, who spilled the beans later while drunk during the ferry ride. Once she knew who Michael really was and his connection to Arthur McCall, it was probably easy to find McCall's lawyer, Sarwar.