FYI: these warnings are on the honorary thai consulates website in the UK now;
PLEASE NOTE DUE TO NEW REGULATIONS NO CONSULATE IN THE UK CAN ISSUE A MULTIPLE NON-IMMIGRANT VISA. CONSULATES CAN NOW ONLY ISSUE A SINGLE
That means ALL year-long, multi-entry Non-Immigrant Visa applications go to the thai embassy in London.
Thanx go to Stuart Hurley from the Expats In Isaan / Northeast Thailand Group (y)
TLDR : Answer Summary
Recent updates indicate that due to new regulations, no consulate in the UK can issue a multiple-entry Non-Immigrant Visa; only single-entry visas are available. All multi-entry Non-Immigrant Visa applications must now be directed to the Thai embassy in London. This change has been in effect since September 2016, and similar regulations apply in other European countries such as Belgium and Switzerland.