• The National Trust for Scotland's headquarters in Edinburgh William R Lindsay, a secretive millionaire who had anonymously given nearly $4 million (2.5m) to the trust in the past 18 months, is understood to have bequeathed his estate, after a lonely death at his home in Las Vegas. Donations from Mr Lindsay, who shot himself in November at the age of 79, contributed to the cost of major projects such as the new Robert Burns Birthplace Museum in Alloway, Ayrshire, which opened last month. While much of Mr Lindsay's life - and the source of his wealth - remains shrouded in mystery, the value of his legacy is likely to be considerable. A fundraiser who works in the United States on behalf of the trust believes it could be worth up to $4m. An NTS spokesman paid tribute to the "long-time supporter and generous donor", but refused to comment on how much - or when - any funds would be available to the organisation. Johanna Gurland, who raises funds for the NTS in the US, said Mr Lindsay had never visited Scotland but was inspired to donate by a passion for the country's history. • 'If you saw him you wouldn't think he had a dime' • Other generous spirits "Like many Americans he had a fantasy of Scotland based on the movie Brigadoon and not too much else," she said. "His family very long back came from Scotland, but it was many years ago, he had no direct connection. He was very interested in history and one of the things that impressed him was the age of the properties." After years of living alone with his dog and driving an ageing car, Mr Lindsay took his own life apparently to avoid going into a care home, Nevada police said. The body of the childless, single millionaire investor, was discovered at his home by Elton Marvin, a barber and one of Mr Lindsay's few close acquaintances, to whom he left his dog, a pug named Midget. Ms Gurland first received a call from Mr Lindsay in 2004. "He said, 'Is this the US office for the National Trust for Scotland? I'm someone very interested in giving, I'm an old man and not well and have a lot of money.' "We get these calls quite often. Most of the time these people are lonely and looking for attention. I was willing to talk to him, but part of my brain was saying it was another nut," she said. Ms Gurland became the chief contact with Mr Lindsay, visiting him just once but talking to him regularly on the telephone, sharing stories about their dogs. "He and I bonded over our dogs and started a friendship based on that. I always kept in touch with him. I think he was lonely, but he wasn't needy." Mr Lindsay told the fundraiser he had met US president Dwight Eisenhower at school, and was interested in the fact that he visited one of the trust's major properties, Culzean Castle, which has an Eisenhower suite, she said.They discussed how the money would support properties like Culzean and the Burns centre. Five years later he made his first gift, of $2m, reported exclusively at the time in The Scotsman, but the trust kept his name rigorously secret. Mr Lindsay was to make another sizeable donation to the NTS months later. A donation of $1.7m was made last February. The NTS is understood to have engaged the services of a lawyer in the US to oversee its claim. "He was a very, very private and close-mouthed man," said Ms Gurland, who estimated the estate could amount to between $2m and $4m. "I would love it if there was a lot of money there." Suggestions that Mr Lindsay was suffering from Alzheimer's could open grounds for a legal challenge to his will. He is said to be survived by a niece and nephew, and has supported two elderly relatives living in Ohio, where he was born. He is understood to have left the trust the residue of the estate after other legacies are paid off, including his home in Henderson, a Las Vegas suburb, in a gated estate where property prices run from several hundred thousand dollars to more than $1m. Lawyers may be seeking to explore family trusts and other bank accounts of a man who had properties in California as well as Nevada, and often used only a post office box as his address. Mr Lindsay's first act of benevolence to a Scottish institution was an unsolicited donation of 1.2m to the University of Glasgow, made through the Friends of Glasgow University Society in New York in 2000. Baffled by the gift, the university used it to fund a post, the William R Lindsay Chair in Health Policy and Economic Evaluation. "We are saddened to hear of Mr Lindsay's death and send our condolences to his family and friends," a university spokesman said yesterday. A spokeswoman for the NTS said: "We confirm that the trust was recently notified of the death of a major donor who wished to remain anonymous. "This individual had been a long-time supporter and generous donor, making substantial contributions for which the trust is hugely appreciative. "Support such as this is vital to enable the charity to carry out it's vital conservation work. The trust is expected to be a beneficiary from the estate."