Mr Tilley, who works for South East Coast Ambulance Service, was giving evidence as a representative of the GMB union.
In January 2021, at the peak of the winter wave of the pandemic, he volunteered to move to Sittingbourne, in north Kent, for three weeks, along with 40 colleagues.
A new variant of Covid which appeared to transmit more quickly had recently emerged in the area, and hospitals were coming under increased pressure.
He told the inquiry that, on one occasion, he had to queue in his ambulance outside A&E for an entire ten-hour shift because there was not enough room to transfer a “heavily deteriorating” patient into the building.
“We’d run out of oxygen, so we’d had to scan the hospital to try and find [more],” he said. “We ordered pizza to the vehicle because otherwise we wouldn’t have had anything to eat.”
Because of lockdown rules at the time, volunteer ambulance crews were sleeping in a budget hotel, with some deciding not to return home to avoid placing family members in danger.
“You had nowhere to go, so it was just the facilities that were there: the television and a phone,” he said.
“You had 12 hours [after your shift] to mull over what you’d been seeing; the queues at the hospital, the poor patients.”