Inspired by a family friend who was a jeweller, Marshall left school at 16 to undertake a five-year jewellery apprenticeship in central London. With four years of training under his belt, he left his apprenticeship early to open his own workshop. Working both independently and for other jewellers, Marshalls big break came two years later, when aged 22, he was asked to undertake a number of large trade commissions for jewellery house David Morris.