Fresh plans have been unveiled for the overhaul of a major London hospital as NHS bosses look to upgrade its crumbling facilities.

St Mary’s Hospital in Paddington is home to some of the oldest buildings across the entire NHS, with some of it pre-dating the establishment of a nationalised health service in 1948.

Parts of the estate are in a state of disrepair and cost £10 million a year in repair bills.

The west London hospital part-closed its outpatient building late last year following the discovery of autoclaved aerated concrete – known as concrete cancer.

In a bid to push a rebuild up the UK Government’s priority list, the NHS trust that runs the hospital has published new images of what a redeveloped site could look like.

At present, the 175-year-old hospital, home to London's busiest major trauma centre and the site of penicillin's discovery by Scottish bacteriologist Alexander Fleming in 1928, is not due for central government-funded works until the 2040s.

The redevelopment, the designs for which have been progressing in stages, will deliver a new 800-bed teaching hospital and major trauma centre alongside an expanded life sciences campus.

Services will be brought together in a taller building, about 30 storeys, that will have a smaller footprint than the current hospital, freeing up space for upgrades to other parts of the estate.

Imperial College Healthcare NHS Trust, which runs St Mary’s, has asked patients, staff and the wider community to comment on the proposal, with the intention of submitting a planning application in spring 2027.

Professor Julian Redhead, chief executive of Imperial College Healthcare NHS Trust, said: “St Mary’s has an extraordinary history of care and medical breakthroughs across nearly 200 years, from the discovery of penicillin to becoming one of the country’s first major trauma centres.

“But much of our estate is now very old and increasingly difficult to maintain, with building failures an increasingly regular occurrence despite spending millions every year on essential maintenance.

“We have a once in a generation opportunity to create a new hospital that meets the needs of our patients, staff and communities and regenerate the whole site into an expanded life sciences campus, attracting jobs and investment.”

Despite the crumbling conditions on parts of the estate, Imperial’s three hospitals, including St Mary’s, are in the final tranche of the Government’s New Hospital Programme (NHP), scheduled for the 2040s.

The trust is hoping that by developing its own application, with funding from the NHP alongside alternative sources, a new hospital may be deliverable by 2035.

It comes after meetings between local MPs and health trust bosses with Government officials in February led to £50 million over three years being signed off to speed up the rebuilding process.

Designs for the proposed scheme have already undergone two rounds of consultation, with a third now being launched.

The updated plans include the integration of research facilities into clinical areas, upgraded arrival and drop-off points and flexible spaces that would enable the hospital to respond to future crises such as pandemics.

The 14th floor of the hospital will be the sky lobby, which the trust says will connect the main clinical zones as well as spaces “for rest and reflection”, such as the sky garden and café.

The masterplan for the wider site will also see the expansion of the Paddington Life Sciences campus, a hub of businesses centred around St Mary’s.

Independent evaluation estimates this could create between 9,000 and 11,000 additional jobs and generate up to £1.3 billion more a year in economic activity.

Two new green public spaces are proposed, Mint Square and Canalside Square, with heritage buildings including the Grade II-listed Clarence Memorial Wing to be retained and restored.

Imperial is running a series of public exhibitions and community pop-up events as it seeks feedback on its latest designs.

An online webinar is also to be held, plus an online survey and a consultation hub in Paddington Square.