Please be advised
your application is currently pending transfer to London,
and you will be contacted further in due course." since Oct-2020 it's around four-month still they not sent my file.
This is a form letter and I doubt they looked precisely at where the file is.
It IS possible it hasn't physically been sent - i.e. if there is not room in London.
But it's also possible it is in a room or vault in London (from looking at my own GCMS notes, although different field office) - they may not use 'received' in London is normal human sense; they may be referring to when logged in system and placed in queue for processing / assigned there (with internal terms like registry).
Or in practical terms: there was more than a four month delay in my case for file to move from 'transferred' to field office and it showing in the system as 'received', even though from GCMS notes it was clear the file had physically been sent and received at the field office.
Unfortunately, knowing that doens't tell you much except that you're still in a queue, just possibly a different one.
If you want to know more, order GCMS notes, although it may not tell you much
of use at this stage.