A new type of immune cell which kills most cancers has been discovered by accident. While analysing blood from a bank in Wales, looking for immune cells that could fight bacteria, the researchers at Cardiff University came across an entirely new type of T-cell.

That new immune cell carries a never-before-seen receptor which acts like a grappling hook, latching on to most human cancers, while ignoring healthy cells.

In laboratory studies, immune cells equipped with the new receptor were shown to kill lung, skin, blood, colon, breast, bone, prostate, ovarian, kidney and cervical cancer.

Professor Andrew Sewell, lead author on the study and an expert in T-cells from Cardiff University's School of Medicine, said it was "highly unusual" to find a cell that had broad cancer-fighting therapies, and raised the prospect of a universal therapy.

"This was a serendipitous finding, nobody knew this cell existed," Prof Sewell told The Telegraph.

Asked if it meant that someone in Wales was walking around completely immune to cancer, Prof Sewell said: "Possibly. This immune cell could be quite rare, or it could be that lots of people have this receptor but for some reason it is not activated. We just don't know yet."