From modest beginnings in the Republic of Ireland, oil and gas explorer Tullow has become a serious player in one of the world's most cutthroat industries, Business Editor Andy Richardson looks at the rise of the firm behind Invest in Africa, Sunderland AFC's new principal partner and shirt sponsor.

FOR centuries Africa's raw materials have drawn prospectors from Europe.

Aidan Heavey, a keen golfer and Manchester United fan, quit his job as an accountant at Aer Lingus in the early Eighties to work at a firm operating a fleet of fuel oil tankers in Tullow, 30 miles south of Dublin.

In 1985, a chat with a banker friend alerted him to opportunities in Africa. Rather than battle for elbow room in the North Sea the newly formed Tullow Oil bought up depleted oil and gas fields in Senegal. Mr Heavey had never set foot in Africa and possessed scant knowledge of the business.

To fund the venture he mortgaged his home and sold his collection of vintage cars. Critics scoffed at the prospects for a company led by a rookie with no financial backers.

Mr Heavey is now fond of reminding people that he is the longest-serving chief executive at a FTSE 100 index firm - heading up a business valued at £13.5bn. Tullow has interests across Asia, South America and Europe, but its largest activities are concentrated in Africa.

Its oil and gas developments are supported by major spending on infrastructure, hygiene and education for the local area. Mr Heavey is a director of Traidlinks, an Irish-based charity established to develop and promote enterprise and diminish poverty in the developing world, particularly Africa. However, the company's community work is founded on business principles.

"You can't work in an area where people are dying around you," Mr Heavey has said.

The company doubled in size in 2004 with the acquisition of Energy Africa and in 2007 made its largest discovery to that point - the Jubilee field offshore Ghana, which experts estimate could yield more than one billion barrels. It also discovered vast oil deposits in Uganda.

Tullow's discovery off the coast of French Guiana in a part of the Atlantic where most people had said that there wasn't any oil forced the industry to sit up and take notice.

Last year it reported record results, including a 35 per cent increase in production and an increase in profit after tax of 670 per cent to £440m.

Tullow Oil at a glance

Sector: Oil and gas exploration.

Founded: 1985 in Tullow, small market town in South-East Ireland.

Chief Executive: Aidan Heavey

Head office: London

Employees: 1,548

Operates in: 22 countries

2011 Results: Sales £1.46bn, profit after tax £440m