He reached the semi-finals of the 1978 World Snooker Championship, at the age of 64, having defeated John Virgo 9–8, Dennis Taylor 13–9 and Patsy Fagan 13–10. He met Perrie Mans and trailed 14–16, but missed a , which allowed Mans to take the frame, and eventually win 18–16. The crucial missed was watched by his brother Joe, who was taken ill after the miss; he was rushed to hospital to undergo a six-and-a-half-hour operation, but died a few weeks later. This would be the last time Davis would reach the semi-finals of the event. Davis closed 1978 with a quarter-final appearance in the UK Championship. He defeated veteran Yorkshireman John Dunning 9–2 before losing to Alex Higgins 9–4.