Gary Griffin, the headmaster of Immanuel College in Bushey, is to retire at the end of the winter term after four years in charge of the fee-paying school.

Anthony Warrens, chairman of Immanuel’s governors, praised his distinguished service and “impressive stewardship” which included steering the college “through the most challenging of periods caused by the global pandemic”.

Michael Buchanan, a former head of Ashford School in Kent and a former deputy head of Highgate School in London, will become interim head of the college in January.

Under Mr Griffin, exam results improved year on year, Mr Warrens said,and there were  “more pupils on the roll than at any time in its history.”

His contribution to the school’s development had been outstanding and his commitment to improvement had been recognised by the Independent Schools Inspectorate, which had classified Immanuel as outstanding in all aspects.

A search has begun for a successor to Mr Griffin, who is 62.