The Iron Hog Challenge involved riding my Harley-Davidson motorcycle to all 28 dealerships in mainland UK during 1-3 May 2014 - a distance of over 1,900 miles in 60 hours. I took the opportunity to raise money for Cancer Research UK's work on immunotherapy. Aimed at harnessing our own immune system to focus its ability on what it already does, not only makes sense. It was an approach that also convinced my brother, Dr Andrew Gregory, a nuclear physicist, who was taken out by stomach cancer in April 2013, aged 48. He died tantalisingly close to taking part in an immunotherapy trial. This effort was made in his memory as a positive step closer to an end to this utterly dreadful disease. Thank you so much to everyone who helped - it's not too late if you'd like to!