An accountant by training, Tullow Oil's Irish chief executive Aidan Heavey has turned the oil and gas exploration outfit into a stock market star - and one that continues to shine despite the recession.

He was a founding director of the firm in 1985 and has played a key role at Tullow since its formation. From its early days in Africa, Tullow grew to become active across the British, Asian and South American markets. In 2006, he acquired Australian company Hardman Resources for £581m, and also bought into the North Sea gas market well before the rise in gas prices.

London-based Tullow is tipped as a takeover target and its shares have held their own through months of stock market turmoil. The company has also made promising discoveries off the Ghana coast and in Uganda. Tullow is now worth £9.9bn. Heavey, educated at University College Dublin, has a stake worth £78m. He cashed in £24m in options in 2008, taking him to £98m easily.