Did you know that Tannoy used exactly the same crossover for both the 12" and 15" Monitor Golds? In different cabinets? That's a large part of why I have my doubts about them incorporating baffle width calculations in their designs.
Anyway, I will making mine 50-52 cm wide, which is quite close to their various widths. The distance to the top edge is something I will have to look at though.
Paul (Reffc) has added some helpful comments over on Lenco Heaven, particularly about tuning, so I hope to do some drawings and volume calculations soon. Old school, with pencil and paper, and a calculator. I know how to use them!
I do appreciate your help, otherwise I would be struggling even more. I grew up in a world without computers, and resisted them as long as I could, so now I find I can't catch up. My working life has been largely spent doing things like signwriting, glass etching and making leaded lights, or in joinery. Hands and eyes, no brain needed. Now it doesn't seem to work!