Ulster Bank chief executive Jim Brown is to leave his role with the Irish financial institution to take up another position within Royal Bank of Scotland.

RBS announced today that Mr Brown would become CEO of Williams & Glyn, a bank being developed by the group in the UK. Mr Brown’s appointment is subject to regulatory approval and he will remain in place at Ulster Bank until a successor is appointed in the coming weeks.

Commenting on Mr Brown’s move, RBS’s group chief executive Ross McEwan said: “Jim Brown will bring a wealth of experience in retail and commercial banking and will lead the business as we move towards an IPO in the second half of 2016.”

Mr Brown, who hails from New Zealand, joined Ulster Bank in April 2011 and has guided it back to profitability and successfully steered it through a strategic review that saw RBS recommit to Ulster Bank last year. RBS had pumped £15 billion Ulster Bank since the crash in 2008.

In an internal note to Ulster Bank staff today, Mr Brown described the past four years as “quite a journey” for him and the bank.

“When I arrived in Ireland from Hong Kong in April 2011, RBS, the Irish market and the Ulster Bank business were all working through the immediate effects of the financial crisis and its resulting impact on both our people and our customers. This period has been hugely challenging,” he said.

He said “difficult decisions” had been made to make the bank “safe and sound” and in returning our business to profitability.

“The strategy we put in place to manage our legacy issues while building a really good future bank for our customers has served us well,” he added. “So while I’m sorry to be leaving Ulster Bank, I am extremely proud of the progress we have made, with many core pillars in place for further growth, including strong capital and funding positions, increasing momentum across the business, improved customer Net Promoter Scores and effective management of our legacy issues.”