Well, I think the best that can be said for the Big Finish audio of Mission to Magnus is that it makes me look forward to hearing all the rest of the BF audio plays I shall listen to this year, because they will be better. I commented a few months back that the novelisation of the unbroadcast story felt a bit padded; Philip Martin has stripped out the padding and got down to the bare essentials, and unfortunately the story still is not a very good one.
This is almost entirely the fault of the script. The introduction of yet another Time Lord with a strange past relationship to the Doctor was a repeated mistake of Sixth Doctor stories (from start to finish – Azrael, the Second Doctor, the Trial scenes) and it is not done any better here than in any of the other cases. The Ice Warriors’ plan is a silly one, astrophysically, and the Doctor appears to deal with it by essentially snapping his fingers. And the women-only planet, which is merely dull in the book version, is actually rather offensive here. (Not quite as bad as The Two Ronnies, but this is not saying much.)
Most of the cast give this rubbish their best efforts – the regulars, Colin Baker and Nicola Bryant; returning guest star Nadil Shaban as Sil; also I thought Susan Franklyn among the supporting cast was rather good (and Maggie Steed at least adequate). But Big Finish took the courageous step of getting child actors to play the child characters, and with the best will in the world, this experiment cannot be described as a roaring success. It is a real shame that Wally K. Daly could not be persuaded to liberate his script for The Ultimate Evil, as I think it would have lifted the quality of the Lost Stories season rather considerably.