Twenty-four members of 4-5 Gray's Inn Square, including seven QCs, are set to join 39 Essex Street in a mass defection which represents nearly half the set.

Confirmation of the departures comes after the two chambers announced they were in "advanced discussions" about a possible combination under one brand earlier this month.

The move will take the total number of members at 39 Essex Street to 118, including 37 silks, and will significantly bulk up the set's public and administrative, environmental and planning, common law, commercial and regulatory and regulatory practices.

The silks joining 39 Essex Street are: Brian Ash QC, John Steel QC, Hodge Malek QC, Peter Village QC, Timothy Lyons QC, Thomas Hill QC and Paul Stinchcombe QC.

It is not yet known what is happening to the remaining members of 4-5 Gray's Inn, of which there are understood to be around 30.

David Barnes, 39 Essex Street's chief executive and director of clerking, said: "Enlarging our operations and bringing together this group of barristers, who have phenomenal experience and reputation in core areas of chambers, means that 39 Essex Street can offer clients an unrivalled service across one of the widest legal practice portfolios in the country.

"This union, along with the launch of a new office in Singapore, is part of an ongoing strategy of growth for 39 Essex Street. It is an extremely exciting time for chambers."

The news follows a string of departures from 4-5 Gray's Inn in recent weeks with two silks – Paul Brown QC and Philip Coppel QC – both leaving for Landmark Chambers alongside public law and planning barrister Lisa Busch.

Eleven King's Bench Walk also picked up a group from the set, with commercial barrister David Bedenham and public law members Heather Emmerson, Charles Bourne and Andrew Sharland joining earlier this autumn.

 Full list of Gray's Inn members joining 39 Essex Street:

• Brian Ash QC
• John Steel QC
• Hodge Malek QC
• Peter Village QC
• Timothy Lyons QC
• Thomas Hill QC
• Paul Stinchcombe QC
• James Ramsden
• Andrew Tabachnik
• Damian Falkowski
• James Strachan
• Jonathan Auburn
• Anna Bicarregui
• Mungo Wenban-Smith
• Michelle Pratley
• Jack Anderson
• Thomas Amraoui
• Ned Helme
• Jennifer Thelen
• Philippa Jackson
• Ben Tankel
• Annabel Lee
• James Potts
• Yash Bheeroo