Thank you very much for your thoughts on this .
Apparently the thinking here is that here's a Thai coming for a UK Passport and the most obvious ID that they want is her Thai Passport . And this has a name that is different from any supporting UK documentation .
She didn't ever change her name to her husband's but documents arrived which by default gave her the husband's surname. Now she has all this stuff saying her surname is ..... Blake ..... but her Thai Passport says Nongiddleboomboom or something of that order .
I can see a clear potential issue - the Thai Passport carrying more weight as an ID than anything else ( such as a Water Bill ) - but getting a definitive statement on this is an impossibility . And the fear is handing over £960 for an application and being turned down on that basis .