The London branch of US litigation leader Shook Hardy & Bacon has almost halved in size following its UK merger with Arnander Irvine & Zeitman (AIZ) as it emerges that at least seven partners have left the office.

The firm now has just 10 London-based partners remaining out of 17 at the time of its merger last summer.

Recent departures include former London managing partner Laurel Harbour, who has returned to the Kansas office alongside litigation partner Sam Sebree. Senior consultant Andrew Daws has also left.

Product liability partner Robert Northrip, meanwhile, is due to return to the US in September.

The latest departures follow the resignations of three UK IP partners – James Irvine, Charles Pugh and Geoffrey Gauchi – who joined the London arm of US firm Howrey Simon Arnold & White in May.

Shook Hardy UK partner Clive Zietman commented: "Those partners working on tobacco claims have returned to the US as they did not need to be in the UK to do the work. We still view the merger as being in its early days and have recently picked up two decent instructions from the US."

However, insiders have put the number of London departures down to the difficulty of building referrals between the two legacy firms' practices.

One former lawyer with the firm said that the differences between the practices made it hard to persuade US clients to use the integrated London practice.