I'm looking forward to the French Spaceplane book, especially since it covers other European projects. I'm looking forward to see what it says on HOTOL although I feel that it needs it's own book.
I's got about 8 pages on HOTOL and Interim HOTOL, but not really anything I hadn't seen before. (But then again, I used to closely follow activities in the RLV/Spaceplane sector professionally back in the day. Actually, some of my work I did on the FSSC-5 and FSSC-16 concepts in the FESTIP program is shown on pages 220 through 222

). A standalone book on HOTOL as well as Skylon would however be welcome indeed.