Can my wife join me in the EU immigration queue to enter the UK, or can I join her in the non-EU queue?

I've seen this question, but the situation there is (as suggested by the answers) different to mine because the question pertains to an EU national's girlfriend. The accepted answer states that married couples should join the EU queue, but somebody in the comments states:

The reason for an eu/non-eu married couple going both to the EU line is perhaps more about the fact that the non-eu spouse is traveling under the right of free movement rather than about a policy of not separating families.

I can't really see if the answer's assertion is correct, or if it applies to our situation.

I'm British and my wife is from Hong Kong. We've been living together in Japan since we got married, and we're travelling to the UK together for the first time. She doesn't have any kind of leave to remain in the UK, etc.

Is she able to join me in the EU immigration queue? If not, can I join her in the non-EU queue?

I'm not sure if this will make a difference, but as it's uncommon in Hong Kong for a woman to take her husband's surname when they get married, my wife has a different surname to me. If this is a problem, would a photocopy of our marriage certificate suffice?

Edit: I got a reply from Gatwick Airport's Twitter page wherein they stated

It is the preference of UK Border Force that family pass through together. As your wife doesn't share your surname, I can't be sure what issue that might present at border control and it may be advisable to choose the non-EU queue. You may wish to call UK Border Force on 0844 776 8537 or ask an agent at the airport for future travelling reference.

Update: I did call UK Border Force on the number provided, but it just goes to a higher level government group who don't really have answers. Essentially nobody I spoke to could say for sure either way.

In the end, we found that yes: we can go through the UK queue together.