Sitting by the swimming pool at the Royal Beach hotel in Eilat, Israel, last month, holidaymakers Tony Abraham and Leslie Collin spotted each other's tell-tale hip and knee replacement scars and began chatting about their respective operations.

When their conversation reached discussing when and where they had their replacements, they could scarcely believe it when it emerged they lived within miles of each other and had both been treated by the same surgeon at the same hospital.

Vivian Feather, sunbathing a couple of loungers away, heard their conversation and joined in. Almost unbelievably, she too had been treated by Aresh Hashemi-Nejad at the Bupa Hospital in Bushey.

To top things off, Mr Abraham's wife, Ruth, works in the hospital's pathology department.

An impromptu knobbly-knees competition took place and, together with their spouses, the former patients became friends.

Mrs Feather, who lives in Whetstone, and had a knee-replacement in 2002, said: "It is not usually my first topic of conversation. My family think it is amazing, and it also turns out that my husband was at primary school with Mr Abraham, who now lives in Stanmore, and they had not seen each other for many years."

Mr Collin, 54, of Hillcrest Avenue, Edgware, said: "We were just sitting around the pool and there were various scars visible. We got talking about the operations we'd had and discovered we all had the same specialist and had been in the same hospital.

"We did not know each other but we have kept in touch since we got back to London and went out over the Easter weekend. You could say we had a bit of a knees-up."