A 30% boost in assets under management to £2.4bn in the six months to March helped Impax Asset Management, the Aim-listed environmentally-focused manager, swell first-half profits by a third to £1.6m despite booking a £1.5m charge relating to a change in tax rules affecting its long-term incentive scheme.

Although the Japanese nuclear disaster in March has focused government attention on the sustainability of nuclear power, the majority of Impax's inflows occurred prior to the Fukushima catastrophe.