Mr Johnson had learning difficulties and started at the supermarket 10 years ago, collecting trollies, before being promoted to working on the tills.

The keen Evertonian lived with his parents in Strand Road, Hoylake, but was saving up for a future with fiancee Kate.

The couple met three years ago at a weekly event in Birkenhead for people with learning disabilities.

Recording a verdict of natural causes, Wirral coroner Christopher Johnson said: “Mr Johnson was fit and healthy with no history of allergies.

“Dr Askar prescribed a course of amoxicillin which he had received previously but sadly, on this occasion, he collapsed while he was in work.”

In a card sent to his parents after his death, colleagues at the supermarket said Mr Johnson was a “fantastic colleague who had the ability to brighten the darkest, wettest days”.

His mother, Doreen, said: “He was just brilliant and everyone loved him. Mark did not just pass through – he made a difference to people’s lives.” His father, Bill, said: “Mark was just a lovely lad. Every Friday he would bring home a bunch of lillies for his mum and put out the bins for her and the neighbours.

“He was full of energy and nothing was too much trouble.

“He was never late to work and, even if he was not in Sainsbury’s, he would go and help out at the corner shop or at his sister’s pub.

“He had a cracking life and I couldn’t have wished for a better son.”