In April 2021, Garry Cogan felt a slow, burning pain move steadily higher through his right arm. It was the start of a major heart attack that doctors warned could shave decades off his life without timely triple-bypass surgery.

Nearly two years later Cogan is still waiting for an operation from Britain's overwhelmed health service, one of millions to suffer as it buckles under the weight of an aging population, a lack of investment and the COVID-19 pandemic.

"It's made me feel very uneasy in myself, very tentative about what I can and cannot do," said the 62-year-old warehouse worker from Colchester, southeast England, who has reduced his working week to three days out of fear he could trigger another attack.