Billys ill-health, which resulted in prolonged stays in hospital during childhood, two heart operations, and eventually, his early death, was caused by rheumatic fever.
There have often been suggestions that Billy's problem arose after he suffered soakings in cold water, but although this could lower his resistance to infection, it cannot cause rheumatic fever, a doctor advised me.
In young children, the condition usually develops as a result of strep throat, in which bacteria cause an inflammation of the throat. This condition is at its height among children aged 5-15.
Nowadays, it is treated with oral antibiotics for ten days. In the mid-1940s, the ailment was not so well understood, and in any case, suitable antibiotics were not readily available in post-war Britain. Had Billy presented with this condition today, he would almost certainly have been treated swiftly and effectively, the doctor advised me.
In rheumatic fever, damage to the heart valves arises from the manner in which the bodys immune system reacts to the bacteria. This leads to a valve malfunction, known as aortic stenosis. The valve narrows, decreasing blood flow, which causes the heart to grow bigger, to compensate for the restriction in the blood supply.
Typically between the age of 40 and 60, the heart is no longer able to compensate adequately, and sufferers begin to experience shortage of breath, fainting (with exertion) and chest pains.
Seriously damaged heart valves may (as in Billys case) require replacement.
The key to the eradication of rheumatic fever is in early detection and treatment of all bacterial throat infections before damaging complications can develop.
In 1963, he became a patron of the Children's Leukaemia Appeal at Stevenage Hospital. I have heard several reports of Billy appearing, unannounced and without fanfare and publicity, to visit children in hospital throughout the country. One lady, whose own daughter suffered from leukaemia, said that Billy attended the funeral of another child, from the same hospital, and slipped away without fuss.
Today, Billy's fans maintain that tradition by raising money for heart research.
Much of the money has been raised through the sale of pens, pencils, key rings, mascots and badges. To see the price list, click here.