Series 9 Episode 6 discussion

[Silktie]

Yeah, I understood the painting provided the location of the file only, which turned out to be Malcolm's address. Maybe, Harry knew someone will eventually come looking for the Albany file, so he set up the dummy file in the archives with the painting in it, which gives Malcolm's address. Then as soon as someone wants the real file, they will have to approach Malcolm. But Malcolm knows never to give the real file to anyone (or perhaps doesn't even have it), so all this does is provide Harry with a heads-up that someone is looking for the file.