Mr Johnston’s eight-year term as managing partner will end on 1 May 2019, though he will continue to act as a consultant to the firm.

Mr McMillan will becoming the new managing partner, with a primary focus on the internal running of the firm and core operational matters such as finance, staffing and IT.

However, Ms Quigley will assume a “parallel role” as senior partner, leading the firm’s overall strategic direction and its external engagement with clients and stakeholders.

Mr Johnston said: “The firm has grown significantly in terms of people and practice areas since I first became managing partner in 2011 and the partners agreed it now makes sense to split the managing partner role into two. This will enable both Roger and Neasa to continue to undertake valuable client work while also driving the growth of the firm.

“Roger will be focused on the internal running of the business while Neasa will lead the firm’s strategic direction and represent the firm in an external capacity. I believe it will be a powerful combination that will deliver fantastic results for the clients and staff of Carson McDowell and I congratulate them both on their appointments.”

Mr McMillan said: “I am delighted to be taking on the role of managing partner at Carson McDowell. The firm currently has 96 lawyers and 167 staff and represents some of the most prestigious and successful businesses and organisations in Northern Ireland, which is testament to our commitment to hiring and retaining the best lawyers. The partners would like to thank Michael for his long service and commitment to the firm.”

Ms Quigley said: “I look forward to the opportunities that my new position as senior partner with responsibility for strategy and relationships will bring. It is essential that Carson McDowell continues to build on its recent success and reputation in the Northern Ireland marketplace and farther afield. The firm has room for further growth and I look forward to playing a hands-on part in that process.”

Following Mr McMillan and Ms Quigley’s promotions, the litigation and corporate teams they jointly led will be headed solely by current joint heads Declan Magee and Richard Gray.