By Will Smale BBC News Online business reporter

Bill Gammell certainly knows his oil exploration

Players of his generation - he won five caps on the wing for Scotland in the late 1970s - are meant to go on to become after dinner speakers, or dabble in some rugby commentary work or newspaper punditry.

By contest, Mr Gammell, who won the entrepreneur award on Monday night, went on to establish oil and gas business Cairn Energy.

Today, the company, which he still leads as chief executive, is valued at �2.56bn ($4.6bn), and the 51-year-old's stake in the firm is conservatively estimated to be worth �30m.

In the last year alone, Cairn Energy's share price has almost quadrupled, and last month the 24-year-old firm entered the FTSE 100 index of the UK's leading companies. Cairn has major oil and gas interests across India and wider South Asia.

It is a swashbuckling story of risk-taking, and the rewards that can come from holding your nerve while all those around you have lost theirs. Not to forget, good old-fashioned hard work.

Definitely Patient

Born and brought up in Edinburgh, Bill Gammell established Cairn in his home city in 1980, as his rugby career was coming to an end.

It was soon a small scale oil and gas firm worth some �6m, with investments in the North Sea and Texas. Only that it just kept on growing.

In 1989 Cairn floated on the London Stock Exchange, and was turning its attention to a potential new market for oil exploration - India.

Finding the oil in India was not however immediately easy, especially in the desert region of Rajasthan, in the north western part of the country.

There Cairn was in a 50/50 joint venture with Anglo-Dutch oil giant Shell. Only the oil really didn't appear to be there in sufficient quality to make it all worth while, so much so that Shell wanted out.

However, Mr Gammell decided to stick to his guns, trust his instincts - and the initial data - and keep on looking.

And this was despite the pessimism he picked up from the job. "I learned two golden rules, double what you are told are the technical risks, and halve what you are told about the upside," Mr Gammell once said.

Striking big

In 2002, Cairn bought out Shell's half of the stake for �4m and increased the drilling.

Mr Gammell's success is just extraordinary... he is very entrepreneurial, and definitely doesn't just sit on his assets Bruce Evers, Investec oil analyst

Oil analysts were somewhat aghast, and by Christmas 2003 the Rajasthan field still wasn't looking good. Cairn had spent �56m - a fifth of the then value of the company - and still not found major strikes.

But in January of this year Cairn struck it big in Rajasthan - up to 1 billion barrels big.

When news of the find was announced, business commentators both praised Cairn and said it was a terrible embarrassment for Shell.

BILL GAMMELL Born in Edinburgh in 1952 Married with two sons Former Scottish rugby international Economics and Accountancy Degree Director of the Scottish Institute of Sport

But Mr Gammell kept his feet on the ground.

"I want to make sure we are humble and don't gloat in our success," he said.

"We can't have an over-hyped situation because then you are going to disappoint."

Impressive friends

Yet Cairn, which announced a pre-tax profit of �22.4m ($40.8m) in the six months to June 2004, did not disappoint, and so far this year has gone on to drill another three "significant" holes in Rajasthan this year.

Cairn has struck it big in India

In addition to Rajasthan, it now has four major oil and gas fields in South Asia - along the India and Nepal border, in Bangladesh, and in south eastern India.

You would think that Mr Gammell's success in such a vitally important industry as oil and gas would make leaders of state want to be his best friend.

And while Mr Gammell is indeed good friends with both Tony Blair and George W Bush, it actually has nothing to do with his current success. Instead, by what is definitely rather amazing coincidence, both were his childhood friends.

Mr Gammell went to the same school as Mr Blair - Fettes College in Edinburgh. Meanwhile Mr Bush used to visit in the school holidays as Mr Gammell's father was also an oil man, and good friends with Bush senior.

For Bruce Evers, oil analyst at Investec Bank in London, the success of Mr Gammell and Cairn Energy is nothing short of "extraordinary".

'Bonanza'

"I have never seen anything like it," said Mr Evers.

"When Shell dropped out of Rajasthan and Cairn decided to stay on, everyone raised their eyebrows.

"The results had been mixed to say the least, but Cairn stuck at it and struck bonanza."

Mr Evers added: "Obviously there was an element of luck involved, but they certainly did their homework and stuck with their convictions.

"Mr Gammell's success is just extraordinary. He is very entrepreneurial, and definitely doesn't just sit on his assets - he is always looking for the next development.

"The Ernst & Young award is entirely deserved, and well done to him."

Accepting the award, Mr Gammell said: "When I look for a member for staff there are four criteria.

"One, that they are brighter than me. Two, that they have a positive attitude and, on top of that, common sense and judgement.