Is a UK visa needed for a UK citizen's non-EU spouse with EU Family Member Residence Card to visit the UK together?

Is a UK visa needed for a British citizen's non-EU spouse (who holds an EU Family Member Residence Card) if they wish to visit the UK together for a holiday?

No. This was a gray area in the law, and the UK's policy was otherwise, until the McCarthy decision of 2014. Now, thanks to that decision, you can travel to the UK under the conditions outlined at Entering the UK as the holder of an Article 10 residence card.

You may also elect, however, to apply for an EEA family permit, as you would have to if you did not have the EU family member residence card. The EEA family permit is free of charge.

Under UK law (The Immigration (European Economic Area) Regulations 2016), regulation 9, a family member of a British citizen is treated as the family of an EEA national if several conditions are met. The conditions are laid down in paragraph 2:

(2) The conditions are that—

(a) [the British Citizen]—

(i) is residing in an EEA State as a worker, self-employed person, self-sufficient person or a student, or so resided immediately before returning to the United Kingdom; or

(ii) has acquired the right of permanent residence in an EEA State;

(b) [the family member] and [the British citizen] resided together in the EEA State; and

(c) [the family member] and [the British citizen]’s residence in the EEA State was genuine.

The fact that you have the article 10 card should satisfy the immigration officer that you meet these conditions.