Weather conditions make pretty pictures and obvious metaphors; snow and icicles than in jubilant sunlight as a rather wintry matron lets herself go, by fairly reasonable degrees, with a springtime lad of half her own age. Between them, as well, loom the tattered remnants of the class barrier. Both live in the Gobham area, but her home is an expensive cottage and his a segment of a housing estate. They meet on a crowded train, where his brash talk amuses her only slightly, because she has been having an early morning tiff with her husband and is heading for London to work it off at the sales. When the boy, on the merest of pretexts, pulls the communication cord and brings the train to a cataleptic halt, her attitude is on a par with that of the railway official who rebukes him subsequently as a 'thoroughly irresponsible young man'. And yet, despite more evidence of his anti-welfare ethos, his joie de vivre begins to grow on her as he dogs her traces through streets and into a department store, explaining to all within earshot that he is celebrating his birthday, and making it crystal clear that his idea of a nice present would be a good time in bed with a bird more mature than the kind he can grab so easily. This she grants him, eventually, after her unexpectedly given her the green light, almost suggesting that it will be okay if they make use of her flat while she does a spot of shopping. They don't. But the substitute pad, gained by a cunning ruse, is of the right colour scheme: orange counterpane and yellow sheets. Afterwards they quarrel - just like marriage, she feels - and separate, knowing that they are in love but that one single day has seen the beginning and end of it.

Someone has been cautious enough to publicise the film as a kind of current variation on Brief Encounter. But, in addition to the coward precedent and the sundry age-gap variations, there is even a distant echo here of spellbound because the boy has a deep-seated complex dating back to childhood when his sister died in circumstances for which he considers himself responsible. In view of all that, to say nothing of one of the most nauseous titles with which a good film has ever been saddled, Say Hello proves as buoyant as the multicoloured balloons that rise into the night sky for the bittersweet finale. Alvin Rakoff has recaptured that elusive charm, so eagerly pursued by filmmakers, so often congealing info go. Not this time. Never a tear is jerked nor a heartstring plucked. A steady line of truth is drawn beneath a light romantic poem. It is good to see how well Rakoff does this, after his valiant try with the more troublesome problems of Hoffman. Of course, he has more room to move, making excellent use of location. Busy streets, trees, a children's playground and a main line station are all conducive to the mood he wishes to establish: the cinematography by Geoffrey Unsworth is blissful. Above all, Jean Simmons is a joy to behold. The film has three choice performances. Leonard Whiting does minor wonders in sustaining the boy's insecure and needful character beneath an almost constant stream of jaunty chat. Evelyn Laye as the woman's mother is just the actress to control some allusions to the freedom - kicks of yesteryear, giving real substance to jests that might come, coarsely from lesser lips. But Jean Simmons takes the day. Her performance is beautifully judged, graduating perfectly through irritation and amusement and ultimate uncloyed emotion. Her face makes no secret of her age; but when the boy persuades her to try wild wigs in a boutique, and to cover her drab-brown propriety of clothing with a mountaingoat fantasy, she banishes twenty years in an instant and shines with an evocation of youth. Moreover, her delivery of each and every line, whether cross or perplexed or disorientated (note her adult and faraway 'Yes, I know' to a tiny lot who has just said 'I've got a balloon'), carries the whiff of reality in circumstances that are leading her to the periphery of a dream.