When Tullow Oil was born in 1985, some of its main founders would have been hard pressed to imagine that the company could ever make it into the FTSE 100 index. It would have been almost as difficult for some investors to imagine that the company’s reputation would ultimately be based on finding oil in Africa, particularly in countries that are not traditionally seen as significant hydrocarbons plays.

But that is exactly what Aidan Heavey, a former chartered accountant and the Irish chief executive of the London-listed company has succeeded in doing, building up a strong portfolio in a continent that has come to the fore as a global exploration hot spot in the last decade.