I've found him a copy of the original Richard Landau script for THE QUATERMAS XPERIMENT.
Val Guest claims (in a Tom Weaver interview) that Landau did virtually nothing  on the script other than add a few Americanisms. In the R2 DVD coimmentary he basically says he wrote the thing from scratch and the moderators make no attempt to correct him. They do however contradict him in the liner notes where there are extracts from the Landau script.

So, presumably, Guest is lying about the extent of Landau's involvement. Why?