A Liverpudlian in Brazil is leading a worldwide campaign against the Halifax, Britain's biggest mortgage lender, in one of the first cases of expatriates grouping together to fight a court action in the UK.

Brian Hazlehurst spends 14 hours a day in his modest flat in Rio de Janeiro, co-ordinating the campaign against the exclusion from free shares when the society was floated on the stock market last year. The campaign now has branches in 29 countries, including the US, Papua New Guinea, China, Poland, Fiji, Mali, Bermuda and Brunei.

Mr Hazlehurst, aged 49, was one of almost 100,000 expatriates excluded by the Halifax from receiving an average of £2,400 in shares. He moved to Brazil 19 years ago after living in Ethiopia, where he was held hostage in 1976 for five months by the Eritrean Liberation Front.

He put £23,000 in the Halifax about six years ago, which means he would have been eligible for about £10,000 when it demutualised. But the Halifax decided to exclude investors living in countries where it found it "onerous" to comply with securities laws or where it considered there was an "immaterial" number of investors - fewer than 1,000.

Using the Internet, Mr Hazlehurst, a freelance translator, started a United Halifax Victims (UNHAV) website, and within months managed to discover several hundred expatriates in similar situations.

Under the slogan, "All UNHAVs shall be HAVEs", he is raising money from members to pay for a barrister. UNHAV's lawyer, Jeffrey Goldberg from Leeds, has instructed a QC in London. Mr. Goldberg is an expert in company litigation and a judge on the northern circuit. If the QC says that Mr. Hazlehurst has grounds, he will start a civil case against the Halifax. The assessment is expected next month.

Mr. Hazlehurst said: "They must have thought that we wouldn't be able to mobilise because we are dispersed all around the world. But with the Internet, it is cheap and fast."

Dennis Milner, a member of the St Albans branch, was told that he had been allocated 239 shares, according to his balance at November 1994. But when he did not receive a share certificate after the flotation, he contacted the Halifax helpline to be told that he had not qualified because he had notified them some months before that he was moving to a temporary address in Holland, where he was on government secondment investigating war crimes in the former Yugoslavia.

"I am absolutely incredulous," he said. "What was even worse was the totally rude, dismissive, arrogant manner in which my subsequent correspondence was dealt with."

Almost 8 million people were included in the £18.4 billion flotation bonanza. Those excluded could have used addresses in one of the 27 "permitted" countries, but many say they were not told or were told too late.

The Halifax also excluded about 240,000 others. Heirs of members who died between the conversion announcement and the flotation got the deceased members' full entitlement only if the heirs had been members for at least two years.

In 1996, the Woolwich, along with the Alliance & Leicester, faced widespread criticism when it emerged that thousands of severely disabled savers would not benefit fully from the share bonanza because their accounts were administered by carers.

The UNHAV's campaign has now enlarged to take account of other categories, bring the potential total number to 314,000, said Mr Hazlehurst. "It is not just about the money any more, it is about the principle," he added.