O'Callaghan has begun the role, while continuing in her position as chief executive of the North Central London ICB, which she has held since 2022.

The merged organisation, which will be called West and North London ICB, will be the largest in England - covering 13 London boroughs and serving a population of around 4.5m people. 

The news comes following the recent appointment of Mike Bell as the new chair for both organisations. He said: 'Frances has an impressive track record in leadership roles across the NHS and is a brilliant appointment for this new role. 

'I also want to thank Rob Hurd, who announced his resignation as CEO of North West London ICB earlier this year. Rob helped establish one of the most successful ICBs - building strong partnerships to improve outcomes for residents. Colleagues have praised Rob's drive to put communities at the heart of the ICB's work, his action on EDI. I wish him well in his next steps.'

O'Callaghan said: 'When people need health services, I want to ensure their experience is positive. We also need to improve the lives of people across our area – particularly those who are experiencing the greatest inequity.

'To achieve these ambitions, I know how important it is to ensure we hear and understand what community health needs are. We have to know and understand our many, diverse communities and populations. This will drive how we commission high-quality services, collaborating with our many local and specialist partnerships to make a real difference.'

Dame Caroline Clarke, regional director for NHS England in London, said: 'Frances' experience leading NHS services in north London over the past few years makes her the ideal person to bring together North West London and North Central London ICBs and to deliver on behalf of our population and staff. I would also like to take this opportunity to thank Rob Hurd for his significant contribution to the NHS in London.'