In all I have read, this story seems to constantly be regarded as a bit of a turkey - and I can't see why.
It seems entertaining enough to me, although the Time Lords continue to be eroded in their WAR GAMES awesomeness.
Peter Cushing was supposed to be up for Borusa, but JNT apparently vetoed it in favour of Leonard Sachs, who had trouble remembering his lines.
Imagine the continuity fun that could have been had with Borusa having the same face as the movie Doctor.
Silly JNT. He really lost perspective sometimes.
Peter Davison has moaned about the coincidence level of Tegan's return, but I always assumed it was the Mara somehow manipulating cosmic events to get her back, just in time for SNAKEDANCE. Then maybe the Black Guardian is up to mischief here too.
Yes, the Ergon is rubbish, but the rest of the story seems fine to me.
And Saward etc seem to moan about the pointlessness of overseas locations, but I liked seeing the show getting away from the UK once in a while; thus adding a little realism to the show, considering that blue box can go anywhere.
So yes, in my opinion, not the bland dud that these episode guide book writers seem determined to make it out to be.
Or maybe it is me that has lost perspective due to rose-tinted nostalgia - and it really is a load of old rubbish?
