A man jailed for more than three decades for drug offences while working in Thailand is hoping to have his sentence cut at a landmark review next week.

Stephen Willcox, 45, from Blaby, was jailed in Thailand after admitting possessing heroin, amphetamines, marijuana and ecstasy while working on the island of Koh Samui in 2003.

As part of a treaty agreement with Thailand, Willcox was allowed to return to the UK in 2007, to prison in Warwickshire, to serve the remainder of his 33-and-a-half-years. However, he was told he would not be considered for parole for at least nine years.

Now, his family – including his wife and five-year-old son – are preparing for a judicial review of his sentence on Thursday, hoping it will be cut down to a period similar to what he would have been given if he had gone through the British justice system. Today, a family spokesman told the Leicester Mercury: "It has been a long wait for the review – it's already been cancelled once – but his spirits are high.

"We're hoping it will set some precedents for other people who have been jailed abroad.

"We've got a very good case together, although I couldn't say what his sentence might be reduced to.

"His wife and son are over here now from Thailand and are able to see him, which has taken a lot of stress away. We get visiting orders pretty regularly, probably about once a week, and he's treated very well in the prison.

"It's obviously very different from the prisons in Thailand.

"If he had been in this country, with the amounts of drugs involved, he probably would have had a suspended sentence. It's been difficult, but we never gave up hope."

Willcox has always maintained the drugs were for personal use, but was advised to plead guilty to dealing under Thai law.

John Davies, who spent 17 years in a Thai prison for drugs offences while maintaining his innocence, is helping to campaign on Willcox's behalf.

He said: "There have been two reviews done for women and each have been successful, but there has not been any man before Stephen."

Mr Davies said Britain's treaty needed a new clause that would allow prisoners to be released if they had served the sentence they would have received in their own country.

He said: "He wasn't even dealing, he was using some stuff himself. It's maybe a year or a slap on the wrist for what he did if it was in this country."

Willcox is now in Rye Hill Prison, in Warwickshire, and has set up an internet diary. In his latest update, he wrote: "Every time I look at my family, the reality of what has gone already, lost forever, hits me.

"The realisation of how my mother, my wife and all my family has fought and given so much support to me in prison, it all weighs so heavy on my conscience, the massive sacrifice all have made and still the nightmare continues."

A Ministry of Justice spokeswoman said today it could not comment on individual cases.