No, Frank had no idea Sacha/Alex would be there. It was just one of his random visits. There are a lot of runaways on the streets of Cardiff, so I would imagine he'd go to places like that. Cites with large runaway populations. Frank is a Detective Chief Inspector with the Met - the Metropolitan Police, a special force only in London. He's a big cheese. I would imagine there are two ways the locals would have dealt with him. Either they would have been unwelcoming, their top ranks rankling at the intrusion and being difficult, or they would be helpful. I think, in this case, given the reasons for his interference, the top ranks would have given the okay and the lowly custody sergeant, although he could have been obstructive if he'd wanted to, was pretty much obliged to co operate. Although he's from a different part of the country and a different force he is a Detective Chief Inspector, so I don't think they would have had any problems with him taking Sacha to an interview room. In reality, due to the fact Sacha is a minor, I would imagine there would have to be two police officers with him and I took huge liberties with that one.