Came across this article this morning. Never heard of this "Legalisation Office". Another hoop to jump through if correct.

http://www.samuitimes.com/british-nationals-currently-in-the-uk-may-be-asked-to-present-their-birth-andor-marriage-certificates-for-a-thai-visa/

I have never heard of anybody needing a certified UK birth or marriage certificate being needed to apply for a visa at a Thai embassy or consulate.

Some immigration offices ask for a certification to get a dependent extension but doing a self certification by doing a statement at the UK embassy suffices.

I would recommend the article is carefully re-read.

The Legalisation Office can be found here

https://www.gov.uk/get-document-legalised

Nothing "new" here.

I got a 3 month multi-entry non-imm O visa last week. Called into Queens Gate in London, waited long enough to get change for Kensington & Chelsea's parking meter (£4.50/hr) and shot out to put the money into the meter while my wife stayed inside with the queue ticket. By the time I got back in she was in a panic as they had called her up with her ticket number and I wasn't there!

They took our completed application form, £125 cash, a copy of the marriage certificate, and initialed the queue ticket and told us to sit down. 2 minutes later they called us, gave us a receipt and said to come back the following day at 11.00am. This we did, put one hour in the meter to park, queued at a window for 10 mins and then they called me up to give me my passport with visa.

Day one - in and out 20 mins, day 2 in and out 10 mins. Cost me £23 in congestion charges and £14. in the parking meter, diesel for a 70 mile round trip and some stress in the first morning's rush-hour traffic queues.

I had taken reams of bank statements with me to prove finances but they didn't ask for any of it, just the fee money and took a marriage certificate photo-copy from us.