The play has an almost legendary status because of its elusive and layered qualities, raising the concern that, like the last episode of The Prisoner, it may actually be beautifully crafted nonsense and not worth sticking with. But be patient: this was directed by Alan Clarke one of the best TV directors Britain ever produced. While he is reputed to have said he didn't understand the play either, he nevertheless manages to pull out the various themes within the piece and weave them together create a genuine sense of enigma rather than mere confusion or tacky suspense.
By the time you reach the final scenes you may have the feeling of having glimpsed something rather than actually seen it. For that alone, it's an experience worth having.
Also worth having is a "what the fuck was that about?" discussion afterwards in which you attempt to describe what it is you've just watched.
- More reading and a brave attempt at a synopsis: Penda's Fen - British Film Institute
- A thoughtful review, albeit one which includes spoilers: Penda's Fen - TV Cream