Complex sentence: The Second World War brought a halt to motor racing in Europe, and the team's Bourne site was used to produce aircraft components; when things got under way again in the late 1940s Mays had moved on to the BRM project.
Split into simpler sentences: The Second World War brought a halt to motor racing in Europe, and the team's Bourne site was used to produce aircraft components. By the time racing resumed in the late 1940s Mays had moved on to the BRM project.