Since its establishment just after the conclusion of WW2, the firm of A. J. Reeves of Birmingham, England has been recognized as one of the world's premier sources for all manner of model engineering supplies. Although marketing issues forced a reorganization of the company in the year 2000, the firm remains in business today as Reeves 2000. An amazing range of model engineering goods is available through the company's world-wide mail order service, which may be accessed through the Reeves 2000 website. This includes books, plans, castings, materials, tools, fasteners and pretty much everything that any model engineer could desire.
The main area in which the Reeves company has relevance for model engine aficionados is that of supplying BA threaded fasteners. One of my own pet beefs with certain owners of classic model engines is their tendency to replace lost fasteners with items having the wrong threads. This is particularly true of British engines which utilize BA or other British threads. There is absolutely no excuse for this - all that is required is to place an order with Reeves 2000 after choosing from their impressive stock of BA and similar fastenings. All forms of machine screws are offered, along with matching nuts, including prop nut sizes like 2 BA.
For my own part, I maintain a stock of such fastenings so that I'm always ready to replace any lost or damaged fasteners on any of my British motors. The retention of these old classic engines in as near as possible to their original condition is important! Please use the correct replacement fasteners! As far as BA items go, you are now aware of a source!