Hospitals were forced to make “major engineering and structural changes” at the height of the pandemic to ensure patients on ventilators received enough oxygen.

Oxygen supplies were put under huge strain globally when Covid-19 hit and thousands of patients needed hospital treatment. But as well as struggling to get their hands on the stuff, it has been revealed doctors in the UK struggled to deliver enough of it to patients due to the “inadequate” equipment many were using in the early days of the pandemic.

“The requirement for high flow oxygen as a method for treating Covid-19 came as a surprise,” Nigel Edwards, chief executive of Nuffield Trust, a health think tank, told the UK’s official Covid inquiry today.

“Both [clinical and state departments] discovered that, in a number of cases, both the size of the pipework to supply oxygen and the machinery that's used to condense oxygen to keep the supply going, were inadequate for the scale of the task that they were required to respond to.

“They responded very well, but they had to make very major engineering and structural changes to be able to accommodate that.”

Following his own treatment for Covid-19, former prime minister Boris Johnson said he had needed “litres and litres of oxygen” to keep him alive.

The need for ventilators to treat Covid patients struggling to breathe prompted a government drive to boost UK production of the machines.

The inquiry has already heard that UK pandemic planning had focused on preparing for an influenza pandemic, rather than one caused by a coronavirus.

Edwards, who was giving evidence at the 20th day of the inquiry’s first module on resilience and preparedness, blamed the lack of adequate oxygen equipment on historic penny-pinching in hospital design.

He added: “I think it probably indicates a broader issue about the way that hospitals in many parts of the UK have been designed and built over the years, which is to really strip out any kind of redundancy to compress the spaces available to save money where that is possible by reducing to the lowest tolerance that sits within the guidance.”

The inquiry continues.