It's always interesting to find out what was written but never filmed.
Incidentally, practically all the cut dialogue was in the novelisation of the episode (in "Scorpio Attack" by Trevor Hoyle).
Maybe he was given an early version of the script, rather than copies of the actual episodes to work from.
I seem to recall that the book came out pretty quickly, but I'm not sure about that. The episodes novelised are "Rescue", "Traitor" and "Stardrive". Could these have been the first three scripts to be finished at the time of novelisation? "Rescue" is a pretty obvious choice for the first section, but surely the next episode would have been a better choice, following on directly as it does (the book doesn't explain how they got back to Scorpio).
The other two novels comprise following-on episodes as far as I can tell. "Blakes 7" (incidentally, am I the only one to write this sans apostrophe?) comprises The Way Back, Space Fall, Cygnus Alpha and Time Squad - pretty completely, I think.
"Project Avalon" contains the episodes Duel, Project Avalon, (about half of) Deliverance and Orac - two groups of two episodes.
When were the three novels published (in relation to the original broadcasts)? The first two of them add details to the episodes (things like "West-Europ Dome ... ump" and Blake being in the engineering division; also Amersat, planet of the dead (Duel). The third novel seems to stick pretty closely to the episodes as televised (or as scripted at least). I think.
Apologies if this email is slightly disjointed - I just realised that it's ten to 7am and I haven't gone to bed yet! Luckily, I don't have to be up until 2 or 3pm (I work 4.30 to 11pm, so I'm in a weird time zone - what area is about eight hours ahead of the UK?)
Good night
Wildean