In order to impose some kind of structure on the catalogue the products are organised by railway company. Pre-grouping products are listed within the 'big four' company that they became constituents of, or amalgamated with. This helps provide a consistent story for the evolution of many coach ranges. It makes the G.W.R. easier to deal with, and it reflects the fact that many designs cross the boundaries.
British Rail produced vehicles that were continuations of 'big four' companies are to be found with the big four coaches. British Rail standard vehicle designs have their own section. Post privatisation vehicles also have their own section. This is not organised by railway company as the continuous cycle of franchisees and the complex web of leasing companies mean few vehicles are tied to one franchise.
Component parts are to be found towards the back of the catalogue, organised by product type. Useful additional items are also mentioned and listed where possible alongside the kits for which they may be wanted.