An interesting case of an old thread being resurrected to bite you on the bum
As far as I am aware, from what I remember at the time, the slip was between Fishponds and Staple Hill. The OP wanted to know exactly where it was, but that I couldn't answer.
I am not entirely sure that the comments of "Colin Radford, 73" should be taken without a cellar full of salt. For example, if you intend to close a line on a given day, and already know what the diversionary route will be, and you are already planning for it, and then a bit of cutting decides to prove Newton's laws of gravity for you on a section of it a few days before the scheduled closure, who would bother to spend the money to clear it?
To imply, as he does, that there was some sort of conspiracy theory at work looks good to conspiarcy theorists, but doesn't really hold water from an accountancy point of view. Why "waste" money on clearing a line that will be closed in a few days anyway?
Likewise his comments on the North Somerset line. The facts were:
1. It was carrying a maximum of three trains per day
2. The Somerset coalfied was on its last legs and wouldn't be there much longer
3. It would probably be cheaper for the railway to possibly take a loss on the coal traffic, or at least lose some of their profit on it because of the longer route via Frome, than it would to have returned the line to service for what was known to be a limited life span.
Furthermore, landslips are not like snow - send a snowplough to clear it?

The snowplough will put right any track buckling and other defects, will it? In fact, why have a permanant way section at all? Just send a snowplough, that'll fix it
Do you think "Colin Radford, 73" is related to that idiot that (I think) Jules quoted on another thread a few months ago who purported to be trained in railway electrification and pontificated that you could stand on a 750DC third rail with no ill-effects? I think he might be ...
I think I'll stick to my version. The slip was beteeen Fishponds and Staple Hill. But I don't know exactly where between Fishponds and Staple Hill.