Addleshaw Goddard has reached a settlement with Grant Thornton partners Nicholas Wood and Kevin Hellard, in their capacity as trustees of the estate of Boris Berezovsky, in a dispute over legal fees.

In April 2015 Master Campbell handed down judgment against the trustees, ruling that they had to pay Addleshaws £12.6m in unpaid fees after the firm represented the now-deceased oligarch in a dispute with Russian metal magnate Vasily Anisimov, the estate of Arkady “Badri” Patarkatsishvili, and investment company Salford Capital Partners.

The trustees had argued that the £12.6m Contentious Business Agreement (CBA) agreed between the firm and Berezovsky was in fact invalid, but the court disagreed, saying that that Berezovsky was well aware of the agreement he had signed with the firm and had he lived would have handed over the fees.

Grant Thornton appealed the April 2015 judgment and the appeal was due to be heard last week, but has now settled.

In a statement Addleshaws said: “The parties are pleased to announce that the proceedings have been brought to an end. The terms of the settlement agreement are confidential and no further comment will be made.”

Berezovsky’s claim revolved around allegations that a significant proportion of assets and funds worth between $2bn and $3bn (£1.3bn and £1.9bn) held on estate by Patarkatsishvili, as well as assets held by Anisimov, were in fact part-owned by Berezovsky. The case settled without admission of liability.

The case settled without admission of liability, but after Berezovsky’s death questions remained over whether Addleshaws’ fees would be settled. It is understood that the firm collected £45m in fees for the cases with a further £5m allocated to barrister disbursements.

The legal line-up:

For the claimant, Addleshaw Goddard

4 New Square’s Nicholas Bacon QC, leading South Square’s John Briggs and Daniel Saoul also of 4 New Square, instructed by Addleshaw Goddard

For the defendants, Grant Thornton partners Nick Wood and Kevin Hellard

20 Essex Street’s Stephen Atherton QC leading 4 New Square’s Robert Marven, instructed by Holman Fenwick Willan partner Noel Campbell