it's a Chinese app Weichat,
Don't really know how they transfer paper applications now. On IRCC website, it states they will send the application to local office after AOR or make the local office the primary processing office in the case of online application. I read on this forum that someone's file was lost on the way to other offices and was found again, can't remember where exactly, but it implies that IRCC did post files out, not scan them and send digital files. if they are still sending your files by post then it may take time.
did you ask London if London is your primary office?