Morgan has been chair of the trust since February 2023, and before the full impact of his health conditions being known, governors had approved an 18-month extension to his term.
He said: ‘I am terribly sad to leave NCIC. I have huge affection for the organisation, not least because of the tremendous care so many dedicated staff have provided to me through my own recent health problems.'
Morgan added: ‘We now have an excellent new leadership team in place ready to take the trust to the next level. This requires energy and commitment, which at the moment I am just not able to provide. With regret I've had to concede that I must continue my recovery in retirement.'
Interim chief executive of NCIC, Trudie Davies, said: ‘Steven has been unfailingly supportive since I joined the trust and he will leave a lasting legacy, particularly in respect of his inspirational drive to rethink how healthcare can be delivered in the 21st century.'
Deputy chair of the trust, Teresa Griffiths, will take the chair role on an interim basis while a selection process for the permanent role is carried out.