I am British guy and am about to go to Thailand with a view to travelling with my girlfriend who is originally from the Philippines but has lived in Bangkok for the last 3 years. We are considering marriage and I guess what I would like to discuss if possible, and anyone can advise, is whether it is better to get married in Thailand or to apply for a fiance visa and for her to come over to the UK for the marriage..?

In terms of financial checks does anyone know to what extent the embassy checks your National Insurance Number..i.e. do they have computer links to the UK tax records or do they accept original Nat Ins documents..?

whether it is better to get married in Thailand or to apply for a fiance visa and for her to come over to the UK for the marriage..?

Whichever is better is up to you; the legal effect would be the same whether in UK or Thailand. If the marriage is registered according to thai law, it would be recognized in the UK. British law on recognition of foreign marriages is governed by the maxim 'lex locus regit actum', which basically means, the law of the land governs the act.