The IFoA aren't as 'highly secretive' as you suggest here, Mpyan1.
Although they don't (yet) reveal the pass mark for an individual paper, they've often said in the past (publically), that 40% wouldn't be unreasonable for an SA paper. However, they've also said (publically) that they have been (and are continuing to do so) try to boost the pass marks up, as they are considering publishing the pass marks at some stage in the future. Last I heard, though, there was still no definite decision on this. Watch this space....
Edit: just found this (old) article: http://www.theactuary.com/archive/old-articles/part-5/richard-muckart-q-26a-3A-making-the-grade/
which suggests that 50% would "ensure a pass". So based on this, bearing in mind that for a relatively easy paper the pass mark would increase anyway, 40% doesn't seem unreasonable (subject to my comment above about boosting pass marks).
Last edited: Jul 14, 2014