When David Greer, Regal Petroleum's latest chairman and chief executive, refers to the company's "somewhat chequered past", he is understating the case. Few public companies have a more variegated recent history.

Nobody expects to get a smooth ride and predictable earnings growth from an Aim oil and gas company. But Regal has jolted even hardened investors in the sector with a succession of top executives, a failed Greek oil exploration, an impenetrable legal battle over valuable Ukrainian assets and on-off negotiations with partners, large and small. Behind it all - sometimes visible, sometimes not - was Frank Timis, Regal's founder and largest shareholder.