Just consider this nonsense. A woman has a Russian passport. Then gets married to a UK citizen and (eventually) gets a UK passport with UK married name. Then, books on BA from UK to Russia. But in what name ?
If uses UK name then gets stopped at Heathrow because no visa in UK passport to enter Russia. Visas are not issued to anyone already a citizen of the country. Shows Russian passport as well but told this is in different name.
If uses Russian (maiden) name then fine to travel outward on Russian passport. But when returning from Russia, gets stopped at airport because no visa in Russian passport to enter Britain. Shows UK passport but told this is in different name.
No facility on a return ticket to use different names in each direction. The ideal solution would be for reservations to have an "alternate name" facility. But IATA/ICAO have never thought of this.
I do hope somebody can tell me the official answer to this combination, because I have asked BA several times and never had any sensible answer to it.