I had a quick search on Ancestry for which census data is available up to 1911 (hopefully 1921 will be added this year). The only M.H.Volks that appears in the listings is Magnus Herman, son of Magnus, brother of George, so there is no chance of confusion and hence it is almost certain that he was the GM at Gosport. In 1911 both sons were still living in Brighton, separate addresses, and Magnus H is an electrical engineer like his father. George is an architect. I wonder if the references in Flight etc. to Volk's shed at Brighton, used for seaplanes, was a joint venture and both sons were involved.