British architecture studio Foster + Partners has been cleared over the death of a man killed by a window that fell from one of its buildings in London, following a five-week criminal trial.

The case concerned the Corniche, a tower block of luxury flats standing close to the south side of the Thames on Albert Embankment, as part of a development that completed in 2019.

Mick Ferris, a 53-year-old coach driver, was killed instantly on 2 October 2018 when he was struck by a 130-kilogram window that had fallen 90 metres from the penthouse of the building down to the street below.

The outward-opening window had been blown off its hinges with the building close to completion, the court heard. A metal restrictor to prevent that from happening had been removed.

After more than 11 hours of deliberation at Inner London Crown Court, the jury concluded that neither Foster + Partners nor the building's design engineer, engineering consultancy Wintech, should be held responsible for the death, the Guardian reported.

But the building's project manager, property developer St James Group, and project engineer, contractor Lindner Prater, were both found guilty of failing in their duty to keep the public safe under the Health and Safety at Work Act 1974. All four defendants had denied the charges.

"An accident waiting to happen again"

The prosecution was brought by government agency the Health and Safety Executive, which had claimed the designers had ignored concerns about the proven danger posed by outward-opening, side-hung windows.

It had argued that Foster + Partners should have been aware of such risks given that glass-covered buildings are "something of a speciality" for the firm.

The designers were accused of failing to consider the "catastrophic" consequences of something going wrong with the restrictor, and of failing to take into account the fulcrum effect of an 85-centimetre-wide window coming loose.

Foster + Partners had maintained that its role in the project was limited to the visual aspects of the design, and that it had not been involved in technical matters.

Jurors were told that in August 2017, just over a year before Ferris's death, another window panel had fallen from the same development with no changes made to the designs in response.

Prosecutor Gordon Menzies had said "it wasn't an accident waiting to happen" but "an accident waiting to happen again", reported the Guardian.

"It's reasonably practicable for clever people to do a simple thing and design a window that doesn't fall out once every year," he added, according to MyLondon.

Strong winds had blown the window wide open, with the oversailing glass clashing with the frame and prising off the hinges, Menzies told the court.

The court also heard that the windows had originally been designed to open inwards, but were changed to outward-openers to avoid clashing with an internal ceiling coffer containing wires and pipes.

"It had no effective failsafe, no reliable back-up. There were many things that could go wrong with the restrictors and if they did, consequences could be catastrophic," Menzies said of the outward-opening window design, per BBC reporting.

"We note the court's decision"

Following Ferris's death, the windows were changed back to inward-opening.

A spokesperson for Foster + Partners said: "Our thoughts remain with Mr Ferris' family, as they have since October 2018. We note the court's decision and are grateful to the jury for the time and care they have taken in considering this matter."

A spokesperson for Wintech said: "While the court has reached its conclusion, the tragedy of what happened remains. It is vital that we continue to reflect and learn, and as an industry, remain committed to strengthening standards and practices to help prevent such incidents in the future."

A spokesperson for St James Group said: "The death of Mick Ferris in 2018 was tragic. Our thoughts remain with his family and friends. We acknowledge today's verdict and will carefully consider its implications."

Dezeen has approached Lindner Prater for comment.

The photography is by Shutterstock.