Henderson Group, the listed UK fund manager, warned this morning it is facing possible legal action over its 2006 acquisition of building contractor John Laing, a black spot against a generally upbeat statement in which the company said it returned to first-half profitability.

The firm said it made £41.6m in pre-tax profits in the first half of 2010, reversing a £2.9m loss during the same period the year before. Andrew Formica, chief executive, said on a conference call this morning the company is expanding its sales and marketing teams and has plans to launch more products.