When I applied for this visa I was (wrongly) refused. Got the medical certificate, police report etc and also took last three years P60's to show my income along with a year's worth of payslips as the Thai Embassy website clearly states money in bank OR evidence of income OR combination of both...here it is...
Bank statement or evidence of adequate finance showing a deposit of the amount equal to and not less than 800,000 Baht or an income certificate with monthly income of not less than 65,000 Baht, (approximately £20,000.00 / annum) or a deposit account plus a monthly income totalling not less than 800,000 Baht. If you send a copy of bank statement, the original reference letter from the banking concerned is necessary.
I was turned away by the most unhelpful person I've ever had the displeasure of dealing with as I didn't have the required amount in a bank account. No amount of pleading or asking them to check their own rules mattered. As she threw my paperwork back at me she included her "guidelines" this was an A4 sheet of paper dated three years previous which made no mention of income or combination of income and savings. So as of January 2018 when I applied if you didn't have enough money in the bank you didn't get your visa.
Take this as a warning...don't waste time going to London until you have checked if their outdated and quite frankly wrong guidelines have been updated