Originally Posted by GUWonder

Never say never. At LHR, I've repeatedly cleared the non-EU lines using my US passport far faster than my travel party members using the EU passport users lines. I mostly do get the benefit of being able to use fast track if I want to do so, and I do have other choices at LHR at times, but even without that, there are definitely times when the EU lines are slower at LHR than the non-EU lines.