Flo's real parents...

Seems many loose ends are left untied in the finale of S2.

Since Colin wasn't arrested, and the police were not going to continue their inquiry, Colin had less to worry about from the blackmailer. Basically, the guy only saw him key the car, I believe, which is rather bad for a barrister, but he was apparently also doing a lot of probono work to help others, so they probably would have gone easy on him. The blackmailer had already gotten 5 thousand pounds, then wanted 20 thousand more, so likely at that point he wasn't going to continue to try to pay him off. Possibly Colin was largely worried that his supposed assault on a woman at work would come out if there was a lot of interest in him, but fortunately the police were able to determine that she had been put up to it by David Walker, because Colin had "asked one too many questions." That revelation was obviously a huge relief to him and a great load off his conscience, so was one of the good things that came out of the investigation, along with Miriam's family finding out why she had issues, and Sara's dad having the opportunity to find out what happened to his daughter and apologize for not being more supportive.