Even though I had already been 'spoken to' by IO staff at Suvarnabumhi and Luang Prabang airport about my travel plans I found the Nong Khai border crossing to be trouble free. So easy. Thanks to
Join the Thai Visa Advice group on FB. The moderators there really know their stuff and take no crap or false information on the page. Follow Tod Daniels, Robert Lagas, James Miller, Ellie Takei and the others there. I learnt everything from them.
yeah I was just gonna post a reply saying almost the same. They need a good job with their own salary monthly into a bank a/c in their name. Letter from employer saying they still have a job when they return. Family, children, husband, wife etc. As many reasons as possible for them to come back to Thailand after the UK trip.