The Hampstead tycoon whose family’s trust gave £5million towards the Royal Free’s new Pears Building put the building’s highest bolt in place at a “topping out” ceremony on Tuesday.

The fixing was turned in by Sir Trevor Pears, the executive chair of the Pears Foundation. It donated money towards the new immunity and transplantation building near the hospital in Pond Street.

The facility, in partnership with UCL, will be one of only five clinical research centres of its kind in the world. Scientists working there are hoping to develop better treatments for cancer, diabetes, HIV and tuberculosis. The project is due to be completed in September next year.

Sir Trevor said: "My brothers and I have been keenly watching this building develop from the window of our offices. We feel confident that the institute will be a fantastic addition to the hospital, Hampstead and London both physically and in terms of what it will contribute to health and wellbeing."

Kate Slemeck, chief executive of the hospital said: "I know that this building will be something that we can be really proud of. Hampstead will truly be a global leader in this area of research and patient care."