The 1960s were a strange time for British cinema - it didn't really seem as though they knew what they wanted to be.

Trailing in behind the 1950s sci-fi and monsters craze in the States, you ended up with a lot of low budget British sci-fi films - some good, some terrible. There were still a lot of war films being made, too, mostly of a more revisionist nature, but these were dying out, and all of a sudden there was the obvious craze for spy films, fashion-conscious comedy-dramas, 'kitchen sink' melodramas and slapstick / naughty comedies.

It could be seen to be a bit of a mess, really, but at the same time it was very exciting that British cinema was capable of such variety. It was also a decade that saw slightly riskier and more offbeat films become a more regular thing, most of which tended to fly under the radar. It's hard to say that Seance On A Wet Afternoon did this - after all, Kim Stanley received a lead actress Oscar nomination for her performance. But it certainly did not and does not receive the level of attention and acclaim that I think it clearly deserves.

Stanley plays a mentally unstable psychic medium who coerces her henpecked husband Richard Attenborough into kidnapping the child of a wealthy couple so that she can publicise her 'powers' by revealing details of her whereabouts. Things take a sinister turn though as Stanley becomes more and more unhinged under the imagined influence of their dead son, Arthur.

When I first saw this (quite possibly on a wet afternoon, funnily enough) I was expecting some kind of supernatural thriller but what it actually is is a slow-burning psychological drama with one marvellously tense cat-and-mouse scene in central London regarding ransom money and an almost unbelievably well acted final scene. Slow-burning it may well be, but it wastes no time at all in getting into the meat of the storyline and demands your immediate attention.

It doesn't have to demand very hard, however, because you are instantly riveted by Stanley and Attenborough. The relationship between these two, in which she initially holds all the sway, is completely absorbing and the way it gradually swings round over the course of the film is amazingly subtle and well performed. This is not a film about a kidnapped girl nor is it really about psychic powers, but more about the mental disintegration of a woman and what her husband will do to try and stop her from slipping over the precipice into utter madness.

Stanley is completely spellbinding here. She was an actress that picked and chose her roles very carefully and actually seemed happier working in TV than film, but if I have seen a better performance than this in any British film from that decade then I certainly cannot remember it. Her performance in the final scene somehow never comes close to hysteria or overracting and yet still manages to be utterly convincing. The sheer, utter confidence she portrays in the beliefs and ideas of her character in the rest of the film means that she never has to trowel on any evil intent - it just comes naturally.

Attenborough, too, is splendid and I hope it is never forgotten just how truly great an actor he has been in his career. Seance On A Wet Afternoon generally will only be mentioned in dispatches when a round-up is done of his finest moments, but it should be right up there with his 10 Rillington Place and Brighton Rock performances as one of his very best.

The only thing that really prevents it from being a masterpiece is the slightly unlikely reaction of the child to being kidnapped and a slightly unconvincing display from Nanette Newman as her mother. But this is still a quite stunning film with two of the greatest screen performances that I can ever recall seeing. Just quite magnificent.