I did see that they have a volume on the Allison engined P-51s in service with the RAF written by forum alum Colin Ford (who also contributed assistance along with other forum members to the P-51B: North American's Bastard Stepchild book). And they also have one on the de Havilland Vampire. They already also have editions on the Hurricane, Typhoon (two editions, early and late), Mosquito (bomber variants) and some Spitfire editions.
From what I've seen, they're like the Polish Wings P-51D book, lavishly illustrated with photos and color plates with info about the planes, pilots and units. But also like the Polish Wings book, they seem to be aimed a lot at modelers and visual learners. Mind you, I don't mind reading text about development of aircraft and infantry weapons, though I'm also heavily a visual learner as well when it comes to how things look and work.
But it does seem that I may need more storage for aviation books in the months to come...