Mr Brown's first winner was Surrey Free Inns, now called SFI. Originally an AIM share, it now has full listing on the main stock market. Mr Brown first bought into the pub group when it was still unquoted, and explains how he was convinced it was a good buy.
"About three years ago, I sat down for lunch with Tony Hill, its chief executive, in the Linden Tree pub in Woking," he says.
"The share price was then around 80p and he was complaining that it was too low."
Mr Brown told the company to hang on and eventually he built up a 6 per cent stake. The AIM trust had to sell out when SFI went fully listed, but it more than doubled its investment. Today, SFI's price (after a number of share splits) is 150p.
Mr Brown's favourite share now is Gold Mines of Sardinia, an AIM company. Six per cent of the fund's money is invested in the stock and he also holds shares in the company privately.
"Everyone's initial reaction when they hear the name of the company is not to believe it," says Mr Brown. "But I've already made some serious money out of it."
He bought shares nearly a year ago at an average price of 15p each. Today they are around 22p.
"The mineral maps of Sardinia, brought out in 1978, showed the island rich in all sorts of minerals except gold and silver," he said. They were proved wrong in 1980 when geology students discovered traces of gold. But the deposits were microscopic, found with technology that only became available after the maps were published.
Australian mining engineers began mining in 1987 and eventually formed a public company which is now listed on AIM.
Mr Brown said: "Lots of exciting news is expected. Its gold reserves are increasing as it drills new sites. Its potential value could be much more than its current market capitalisation of around pounds 30m. I hope to pay off my mortgage with the profits from my investment."
Who's who: Bill Brown
Brought up in Scotland, attended Glasgow University
Trained as an accountant with KPMG in Glasgow
Moved to London in 1988. Joined Invesco Ventures, advising on venture capital investments. The company was acquired by Baronsmead in 1993, which later became part of Ivory & Sime. Last year, Friends Provident took over this Edinburgh-based investment group.
Mr Brown also serves on the London Stock Exchange's AIM Advisory and AIM Appeals committees.