Simple question, complex answer!
The aim of the spreadsheet I update (I am not the 'owner') is to track Outland Spousal Sponsorship applications that we would expect to be processed ultimately by the London visa office. When I say 'we would expect', in a perfect 'non-backlog / visa office overload' world, all applications where the PA is either British or Pakistani would be processed by the London Visa Office.
As I am sure you know, ALL spousal sponsorship applications go first to the 'Case Processing Centre' (note, NOT a visa office per se) in Mississauga where they decide on whether the sponsor is acceptable or not. NORMALLY, once they have decided, they forward the application onto the appropriate visa office that corresponds to the nationality of the PA for PA assessment, approval and ultimately, visa and CoPR issue.
All of the above is in an ideal world! Now it is well known that London have backlogs and sometimes these become so severe that Mississauga instead either retain the paper and process the PA part themselves (so acting as a visa office), which is not common, OR they may pass the paper to Ottawa VO for PA assessment (more common than processing in Mississauga). One gets the impression that if London is having a hard time, applications are first handed off to Ottawa and only in extremis are they processed by Mississauga. Of course the people applying can in no way influence or request a particular office!
That is why you will see on this spreadsheet sometimes London, Ottawa or Mississauga. But the common denominator for the spreadsheet is that based on the PA's nationality, one would normally expect them all to be processed in London.
Hope that all makes sense.
