Why can't I apply for a Thai visa online through the London Embassy while currently in Thailand?

You need to apply while outside of Thailand.

They will want to know where you are physically present…..that’s where you apply.

If you want to save money and can't afford the flight to Vietnam or Cambodia, why not take the bus to Laos? It might take a few hours, but it's not expensive, and you can safely apply for a visa there. You might have an interview, but you're legal, so nothing can happen to you, and after that, you'll have five years of peace.

You're meant to apply in the country you are currently in. But the UK only requires driving license to prove your address. But you will also need to provide proof of flights.

Thailand doesn't allow it.

Your IP address will tell them where you are applying from...you may get by with it...but maybe not

I got asked for my boarding pass to the UK from my last trip to Thailand, and a copy of the exit stamp from Thai immigration

If you get caught in Thailand while applying you're gonna have a hard time, don't play stupid games, they have you registered entering the country.

Up to you, but directly from the Thai Embassy in London website in the English language version:

"...

1.) All applicants must be residing within the UK/Ireland/UK territories when apply for the Visa. The Royal Thai Embassy has the right to cancel the visa applications should you fail to provide the evidence of your presence within the UK/Ireland/UK territories while applying for the visa.

...

2.) The Royal Thai Embassy, London reserves the right to request additional documents / interview in person at the Royal Thai Embassy, London, and amend visa categories as deemed necessary as well as reject any application without prejudice.

...

3.) The applicants must provide genuine documents and information. If the applicants are found to provide false documents or give false information, their applications will be rejected and be reported for further determination of appropriate action and future prohibition to enter the Kingdom of Thailand.

...."

> 18de2bab23

You can only apply for a visa using the consulate that covers your location even though all applications are done on line. What's more you have to remain in that location until the process completes. If you want to apply via the consulate in London you need to get yourself back to the UK before you apply

You have to apply in the country you’re in. If you’re in the UK the apply to the London one. If you’re in Vietnam you go to that embassy