Stephenson Harwood is facing a counterclaim by the trustees associated with British property mogul Robert Tchenguiz, whom the firm is chasing for more than £6 million in unpaid legal fees.

The firm last year lodged a High Court claim against Tchenguiz’s trustees for unpaid bills under a retainer, including for its work on an ultimately unsuccessful 2015 court case involving the trusts’ former business partner, Abu Dhabi investment company Aabar.