Northern Ireland's top civil servant, Sir Malcolm McKibbin, is to step down next year after more than half a decade in the job.
McKibbin took up post as head of the NI civil service – a separate organisation from the UK civil service – in 2011, overseeing the work of nine government departments and more than 23,000 officials. He will leave office at the end of January 2017.
Northern Ireland's first minister Arlene Foster said McKibbin – who served as the permanent secretary of Northern Ireland's Department of Agriculture and Rural Development before taking on the top job – had been "instrumental in helping to lead and reshape the Northern Ireland civil service" and said he had "displayed the best attributes of our public servants".
Interview: Dr Malcolm McKibbin
Malcolm McKibbin on the Stormont crisis and his "most difficult" year as head of the Northern Ireland civil service
Foster added: “He oversaw the reduction in the number of government departments from 12 to nine, reduced the size of the civil service by 17% through the Voluntary Exit Scheme, saw major growth in online public services and helped the Executive move towards an outcome focused Programme for Government.
“I thank Sir Malcolm for his public service and dedication to us and wish him and his family well for the future.”
McKibbin told Civil Service World last year that 2015 – which was marked by political turmoil at Stormont – had been probably "the most difficult" since taking on the job.
"We started the year with optimism having secured political endorsement for the Stormont House Agreement," he said.
"However it quickly became apparent that there were some intractable issues around welfare reform that threatened the stability of the devolved institutions and we were in danger of running out of money.
"At the same time, due to the financial pressures and the need to reduce the paybill we have been managing a voluntary exit scheme which will contribute to an unprecedented reduction of 16% over two years.
"All of this has required strong leadership, rigorous programme management and a relentless focus on resolution and finding a way through, both administratively and politically. No-one involved would say it has been easy."
In a statement announcing his departure on Wednesday, McKibbin said it had been "an honour and a privilege to successfully lead the civil service through its most radical reform programme in over 40 years".
He added: "It has been an amazing experience and I have enjoyed wonderful support from all my colleagues.”
Sir Peter Housden, who led the devolved administration in Scotland as permanent secretary from 2010 to 2015, also paid tribute to McKibbin, telling CSW that he believed the Northern Ireland civil service head had combined "real strength of purpose with the ability to inspire".
"Malcolm McKibbin has been a remarkable leader in Northern Ireland – a skilled facilitator in negotiation with the imagination to see beyond immediate pressures whilst sustaining delivery," Housden said.
"In recent times, he has been at the heart of the Fresh Start process and a prime architect in the adoption of an outcomes framework for the Programme for Government 2016-21.
"He has streamlined the departmental structure and commissioned an ambitious programme of leadership and organisational development to enable the Northern Ireland Civil Service to build on its many strengths in the new environment.
"At a personal level, he combines real strength of purpose with the ability to inspire, and never loses his engineer's eye for the practical detail of a situation. He will leave a very strong legacy and will I am sure have an enormous amount to contribute to public life in the years ahead."
It was announced last month that Sir Derek Jones – permanent secretary to the Welsh Government – is to leave office in the coming months, four years after being appointed in 2012.