SJ Berwin real estate head Jon Vivian is leaving the firm for Irwin Mitchell alongside a three-partner team.

Vivian, one of the firm's most well-respected partners, is joining the top 30 firm along with fellow real estate partners Lewis Myers, Rob Thompson and Jo Footitt.

Vivian's move comes amid ongoing merger discussions with New York-based law firm Proskauer Rose. It is understood disagreements with the firm's real estate team, which does not completely back the tie-up, is a contributing factor as to why the discussions have not progressed to the next stage.

Some partners in SJ Berwin's real estate department have expressed opposition against the currently pending US merger plans worried property will lose focus in a combined firm, whilst having been a key focus for SJ Berwin.

Vivian commented: "I see this as a very exciting opportunity to do something which is different and to build up a first-class team with a first-class real estate service for clients. Genuinely that is the main attraction for me."

SJ Berwin had denied that Vivian and his team had resigned as late as Friday.

Vivan has become one of SJ Berwin's most senior figures since joining the firm in 2001 from CMS Cameron McKenna. As well as recently replacing Bryan Pickup as head of SJ Berwin's real estate practice, he also held a place on the firm's strategy board. He works with key clients including The Crown Estate, British Land and SEGRO.

Myers also held a management role at SJ Berwin as part of the London management committee.

SJ Berwin and Proskauer have been in lengthy merger talks since the beginning of this year, with "cultural differences" cited as a major hindrance as to why a merger has not yet been outright proposed to the respective partnerships as yet.

Commenting on the hire, Irwin Mitchell head of business Niall Baker said: "This is an important development for Irwin Mitchell and underlines both the strength of our firm and our strategic direction. Jon and his fellow partners have one of the strongest reputations in London as real estate lawyers acting for blue chip quality clients, such as British Land, Gazeley and SEGRO. This is another step along the way to putting Irwin Mitchell firmly on the map as a leading provider of real estate legal advice."

Following the departure, SJ Berwin has appointed former head of real estate Bryan Pickup and planning specialist partner Simon Ricketts to jointly head up the real estate department.