Correct, Thailand, unlike the Philippines, collects biometrics, meaning your face and fingerprints will hit to the same individual, regardless of what passport he or she carries. That's what people mean when they say "everything is in the computer". What do you think they take your fingerprints for at the airport? For fun?
"new one" because OP is viewing information from a bogus website! It is NOT true! The dead give away is the so-called "passport countries" which purports that only some cherry-picked nationalities are eligible for the DTV. It's false. I'm not in that list of countries but I got my DTV without issues.
Anonymous participant That's NOT the official website for the DTV!! That website claims some countries are not eligible for the DTV which is NOT true! Source: I'm from one of the African countries omitted in that website, but guess what: I got the DTV! Also, my employer is in another country which is not my home country. Also, my bank account is NOT in my home country. But I was still approved!
Haha people don't even read the terms and conditions of the e-visa website. No where do they mention an "appeal" process for rejected or cancelled applications.
I got mine on workcation basis too and actually spend little time in Thailand as I have other stuff to take care of in other countries, so I'm always coming in and exiting. So far no checks are being done (at least not on me) even though I'm using a weak 3rd world passport. You being British should be fine.
Why did you feel the need to use a "legal firm in Thailand" for the DTV? The requirement is that the applicant does it his/herself from OUTSIDE Thailand. This is why Thai visa agents hate the DTV: it's because they can't get a cut out of it. But here you go.