The mother of a British woman jailed for heroin smuggling in Thailand has held a candlelit vigil at the gates of Downing Street.

Doreen Gregory hopes the event, marking her daughter Sandra's eighth year in prison, will persuade the government to back her appeal for a review of her daughter's 22-year sentence for smuggling 3oz of the drug.

About 30 supporters want an official endorsement of Ms Gregory's appeal to the King of Thailand for a review of her sentence.

The former teacher, from Pitcaple, Aberdeenshire, spent the first four years of her jail term at the notorious Bangkok Hilton, but was transferred to Cookham Wood Prison, Kent, in June 1997.

Unless Thailand shows clemency, the 34-year-old must wait until December 2003 before qualifying for parole, by which time she will have spent a quarter of her life in prison.

Mrs Gregory, 62, said: "I spoke to her last night on the telephone and she was overwhelmed with the support she has got.

"We do not and have never condoned what Sandra did, but she should not have been punished in this way."

She added: "We believe that if the Foreign Office added just one letter to our appeal then the King of Thailand would take notice. We just hope Tony Blair is watching."

If her daughter had committed a similar crime in this country, her sentence "would have been a maximum of four years, with parole after two".

"She must be one of the longest serving female prisoners in the country apart from Rosemary West and Myra Hindley, and just for three ounces of heroin," she said.

"Our aim is to bring to the attention of the prime minister Sandra's plight.

"It's also to highlight the fact that she is going into her eighth year in prison."

Mrs Gregory said her daughter had appealed to the King of Thailand about three years ago for a review of her sentence, but had so far failed.

Failed appeal

According to Mrs Gregory, supporters travelled from across the country for the vigil.

Letters from supporters, including her husband Stan, were due to be handed to Mr Blair.

The campaign has already won support from 60 MPs, 30 MSPs, leading church groups and Scottish human rights groups.

And the case was raised last month in the House of Commons by Mr and Mrs Gregory's MP, Liberal Democrat Malcolm Bruce, who said the sentence should be cut to 10 years with parole granted immediately.