Electron beam welding method and apparatus

A method of electron beam welding a plurality of secondary components to a primary component. The method comprises: (a) on a first weld path which defines a respective section of the primary component to be welded to a first secondary component, forming, by electron beam welding, a spot weld which joins the primary component and the first secondary component at a respective spot weld location on the first weld path; and (b) on a second weld path which defines a respective section of the primary component to be welded to a second secondary component, forming, by electron beam welding, a spot weld which joins together the primary component and the second secondary component at a respective spot weld location on the second weld path. Each of steps (a) and (b) is repeated at least once, in any order, so as to form, on each of the first and second weld paths, a respective set of contiguous spot welds arranged along the respective weld path. Each successive spot weld is formed while one or more of the previous spot