it was the old system. Probably up to late 2008(?), we had to apply for the HSMP approval letter from the homeoffice in the UK first. Once they granted you the letter, you used it to apply for the visa/EC at the UK embassy (via VFS in Bangkok). The good thing is that I could delay my travel to come to the UK as the HSMP approval letter was valid for 6 months and when I applied for the visa/EC, I could defer my travel up to 3 months. so my HSMP was granted in Sep08, my visa started mid April09.
with your case, you just send all of your supporting doc to the UK embassy...one stop service.