Bryn Graham
I googled METV. The site that popped up was for 5, 10 of 20 years. How do you get one for 6 months and at what cost? Can it be had for an unlimited number of years or at least before they change the regulations again.  
TLDR : Answer Summary
To apply for a 6-month Multiple Entry Tourist Visa (METV) for Thailand, you can use the online eVisa program through the Thai consulate website. It's important to check the specific consulate, like the one in London. While some expats have successfully obtained multiple METVs, experiences vary, and approval can depend on the discretion of the consulate. It's advisable to experience the visa's duration provided before seeking to apply for another or a different visa option. Costs associated with the METV may vary, so it's best to consult the consulate's website for the latest details.