Originally Posted by
JFSV
As mentioned above, it is very rare (in my experience) for the non-EU lines to be emptier than the EU lines. But if they are indeed emptier, then there is no rule or otherwise that I am aware of that would enable the immigration officer to turn you away or make you go to the EU line. If that happens, I would seriously raise this with the chief immigration officer.
hope this helps
Done this a number of times now, at Heathrow T2, Luton and Gatwick. No issues whatsoever. However, on my two most recent entries, both at Stansted (where the EU queue was packed, and the non-EU queue empty), I got scolded.