Two leading barristers are quitting the newly merged set of One Paper Buildings and 2 Crown Office Row to join rival 4 Paper Buildings.
Dr Michael Powers QC and Dr Evelyn Pollock are understood to be unhappy at the way the merger is progressing and have taken the decision to leave.
The decision to merge was taken in November last year and the set is now integrating the 73 tenants to create Crown Office Chambers.
Powers is a leading clinical negligence and product liability silk, renowned for his expertise in pharmaceutical law. His client list includes CMS Cameron McKenna and Linklaters.
Pollock is also a personal injury/clinical negligence specialist who is a part-time chairman for the Independent Tribunal Service.
The new tenants will be a boost to 4 Paper Buildings, which in October lost one of the top professional negligence and information technology barristers in the country, Nicholas Davidson QC to rival Four New Square.
In a statement Powers says: "This is a time of change for the bar. In order that the best service is provided to our clients it is important for specialists to practise in strong teams."