Anthony Flannaghan, 33, of Nuneaton, Warwickshire, was convicted of possession of drugs with intent to sell and given the death penalty.
Stephen Wilcox, 39, of Blaby, Leicester, had his life term for possession reduced after a guilty plea.
Flannaghan had denied the charges, involving heroin, ecstasy, and amphetamine, and is planning to appeal.
During a raid at Wilcox’ home on the island of Koh Samui, police found 1.2 ounces of heroin, one ounce of marijuana, 14 ecstasy tablets and 11 tablets of methamphetamines.
