score:1
I believe this Freedom of Information response, as of 8th May 2019, provides some 'official' light on this question: https://www.whatdotheyknow.com/request/queue_allocation_for_britishnon.
It says that
"..Non-EU/EEA passengers who are travelling as the family member of a British citizen or EU/EEA national may join the EU/EEA queue, subject to local queue management arrangements. .."
This suggests that users need to identify these "local queue management arrangements" from the specific border sites independently/separately.
I would be grateful if anyone could present here from the official documents (https://www.gov.uk/topic/immigration-operational-guidance), or any other official state sources, evidence that border sites are indeed allowed to set their own queue management arrangements locally.
Having said the above, however, I have received from the Border Force (as the UK immigration agency is called today) official information that affirms that
"At ... UK airports non-European Economic Area (EEA) family members travelling with their direct EEA family member should remain with their family",
and that they ask the public
"...to speak immediately to the operational manager, one of whom is always on hand at major ports of entry to deal with matters of this kind...", if there is any dissatisfaction with services.
Upvote:1
I have never seen an international arrival in the UK where you didn't have a queue manager guiding people where to go. As an accompanying family member of a UK/EU citizen, you are generally admissible to their queue but if in doubt, just ask the person running the queue.
It is pretty normal to ask them, and their word matters more than what is going to be said here. The local queue management arrangements that you quote in this answer are exactly that.