So, let's be clear: Spence and Kate are not model sweethearts. Yes, there were times when they lived together, though quietly because Tracy had an existing marriage that he would not end (he was a fearful Catholic). But Hepburn had her own fierce need for independence. She had been married once, as a young woman. It hadn't worked and it put her off further experiments - though Howard Hughes came close to wooing her. But Tracy and Hepburn were not natural or constant kindred spirits. Their affection and fellowship were deep, but they did not prevent or end Tracy's ruinous alcoholism or his occasional infatuation with other women. (He actually came closest to divorcing so that he could marry Gene Tierney, his co-star in a bad picture, Plymouth Adventure, and possibly the worst mate he could have chosen - Tierney, alas, was very unstable.) Nor should we pass over other romances in Hepburn's life, or her serene assumption that she was free and independent - which, some said, meant flat-out selfish.
Of course, the chemistry in their acting is palpable, complex and a delight. Only a few years before meeting Tracy, Hepburn had been dismissed as "box-office poison" by Variety. She was not then a public favourite; nor was she regarded as a naturally romantic actress. It is equally the case that Tracy had often been a solitary figure in his best films, and a man's man - a priest in San Francisco; on the run in Fury; a fisherman in Captains Courageous; a priest again in Boys Town; the demon in Dr Jekyll and Mr Hyde. In other words, the tart romantic comedy of Woman of the Year, with its strong emphasis on verbal sparring, was something fairly novel for both of them (though Hepburn had started on it in Philadelphia Story).
The least known and perhaps the most interesting film in this package is Keeper of the Flame - not a success in its day, but a remarkable war-time film that does not refer to war. In a country town, a great man has just died - he was a tycoon, but an inspirational leader, too. Hepburn plays the widow, Tracy is a reporter who attends the funeral and begins to wonder if the legend is the whole truth. They grow closer as Tracy discovers that the great man was bogus and a tyrant. It was adapted from a novel by Donald Ogden Stewart, and it is a sombre work, aware of how easily fascistic leaders could sway America. It is also one of the films in which Hepburn looked most beautiful, and Tracy beholds her with a silent but unquestioned love.
Adam's Rib is the masterpiece, a nearly perfect marital comedy (the pair play lawyers who become opponents in a case that involves the delicious Judy Holliday). But Adam's Rib was co-written by Ruth Gordon and Garson Kanin and it was Kanin who published a "tell-all" book, Tracy and Hepburn, in 1973 (six years after Tracy's death - he was only 67, but seemed older). Hepburn didn't like or approve of Kanin's book, and it is not always accurate; but it helped a lot in the final sainthood that descended on Hepburn, assisted by her own book, Me, and by a book written by Scott Berg, after Hepburn's death.
We still lack a good life of Tracy. The best available, by Larry Swindell, was published in 1970. But a lot more information has become available since then to spell out the torment of Tracy's life, his occasional cruelty to anyone in his circle, and Hepburn's wary sense in leading a separate life. None of this alters or lessens the films. But what we see on screen is the wonderful way in which warring, lonely people sometimes fall in love and stay there - just. We now deserve that much candour on the real, awkward lives.
Katharine Hepburn and Spencer Tracy four DVD box-set, £29.99, www.hmv.co.ukReuse content