Commercial chambers One Hare Court and chancery commercial Serle Court Chambers are set to merge in February.
Lord Neill of Bladen QC, head of One Hare Court, will lead the 44-tenant, eight-silk set which will take the name of the larger set, Serle Court.
Charles Sparrow QC, 74, head of Serle Court, is retiring at the end of the year. Helena Miles, chief executive of Serle Court, says: "We were in the process of deciding who would be the new head of chambers so it actually works in our favour."
Miles confirms that high profile financial services barrister Julian Malins QC of One Hare Court is not going to join the new set. A Hare Court source says Malins has applied to become an alderman, a role which requires a City base. The move to Serle Court's New Square premises would bring him outside the square mile.
The set will be based at 6 New Square, Lincoln's Inn. Miles says: "We are hopeful that we will be able to secure accommodation nearby as some is coming available at 7 New Square."
Michael Briggs QC is chairing the new management board which became operational this month and will consist of Richard Southwell QC, Helena Miles, Richard Walford, David Drake and Dominic Dowley. Miles says the board will also have a senior clerk representative who has yet to be chosen.
Marketing, finance, pupillage and tenancy committees are being amalgamated.
Lord Neill says: "This is a unique move. Never before has there been a merger of a leading set from Lincoln's Inn with a leading Temple set. The artificial barriers between commercial practice in the chancery division on the one hand, and in the commercial court on the other, are increasingly outmoded."
Christopher Symons QC, joint head of 3 Verulam Buildings, says: "One Hare Court has been very small for a long time. The new chambers will be smaller than ourselves but obviously it is moving much closer to our sort of size.
"At the commercial bar I think that people will be very hesitant to make a juggernaut sized firm of 100 people, although it's important to be large and strong."