Bryan Cave Leighton Paisner contentious construction and engineering partner Catherine Gelder has left the firm’s London office to join CMS—the third partner resignation from the London base this month.

Gelder, who had been a partner at legacy Berwin Leighton Paisner since 2012, had spent her entire career at the firm after joining as an associate in 2002.

She was seconded to the Olympic Delivery Authority for a year during 2008-09, where she advised on issues arising out of the £9 billion ($11.72 billion) redevelopment of east London for the London 2012 Olympics.

Her exit from the firm follows that of former fellow contentious construction and engineering partner David Robertson and structured finance partner Rachel Kelly earlier this month, following the completion of Berwin Leighton’s merger with the U.S. firm Bryan Cave this April.

Robertson, who specializes in disputes and arbitration within the offshore and onshore oil and gas, power, water, road and rail sectors, left to join White & Case’s London office, while Kelly left to join McDermott Will & Emery’s London base alongside counsel Kerry Pettigrew. Kelly was the first partner to leave the London office of legacy Bryan Cave since the  Berwin Leighton merger went live on April 3.

Last month, Bryan Cave Leighton Paisner bolstered its London base with the hire of Mukul Chawla QC who previously led the serious fraud office team investigating Libor manipulation, and conducted the first Libor manipulation prosecutions in the U.K. The firm has also hired family law partner Elizabeth Hicks from Irwin Mitchell to head up its London private client practice.

Other contentious construction and engineering partners in Bryan Cave Leighton Paisner’s London office include Bob Maynard, Caroline Pope and James Clarke.

The Berwin Leighton-Bryan Cave merger created a firm with combined revenue of more than $900 million, 32 offices across North America, Europe, the Middle East and Asia, and more than 1,600 lawyers. The new firm operates to a calendar year-end using U.S.-style cash accounting, with the legacy U.K. arm ditching both its April financial year-end and accruals accounting system as well as its lockstep.

Bryan Cave Leighton Paisner and CMS declined to comment.