By Graeme Murray & Megan Banner A quick-thinking doctor cycling home from a night shift sprang into action and saved a man’s life in the street. Grant Williams, a fitness instructor, had been out training for a half marathon in Manchester when his heart suddenly stopped and he collapsed. Doctor Melanie Hamilton was cycling home after working at Alder Hey Children’s Hospital and noticed others surrounding Grant who was “fighting for his life” With the aid of another doctor from Arrowe Park Hospital, Melanie began CPR chest compressions and brought Grant back around. But he suffered a second car…