Last Night's Viewing: Mixed Britannia BBC2, Burnistoun BBC2

George Alagiah really loves the historical present. He was at it all the time in Mixed Britannia, introducing his case histories of love and prejudice with novelistic little scene-setters: "It's October 1959," he would say over archive footage of a London terminus, "and Paddington Station is busy. Scanning the departures board for her train, a nervous-looking woman hurries towards the platform. In one hand she carries a suitcase and holding the other hand is a pretty two-year-old – a mixed-race child." It is, I guess, intended to bridge the gap between then and now, though in one sense it's oddly counter-productive, since one of the consistent themes of this programme has been how far we've travelled in just a few decades. Fifty years ago, the pretty two-year-old, Rosemary Walton, was being handed over to social workers to be taken to Cardiff – an embarrassment in human form. As the result of a white woman's adulterous affair with a black man, she wasn't wanted anywhere – and even in care she found herself on the fringes, accepted neither as white nor black.

At the end of last night's episode, Rosemary filled in her census form in front of Alagiah, ticking the box for White and Black Caribbean with a sense that her existence had at last been officially acknowledged. But hers wasn't the most triumphant story in a programme that was essentially about social pioneers – and often very courageous ones, too. When Pamela and Shafiq began courting, for example, in the Sixties in the East End, they had to walk a gauntlet every time they went out. It might have been all right for Shafiq to work in the local Wimpy (and to serve the National Front skinheads who needed to top themselves up for another bout of hatred), but it wasn't alright for him to go out with a white girl. Pamela had to issue her father with an ultimatum – accept a Bangladeshi son-in-law or lose a daughter – and the emotional strain of that confrontation could still bring her to tears.

That willingness to put human values above tribal ones could be found at both ends of the social scale. The Duchess of Richmond also appeared, to talk about her adoption of mixed-race children who otherwise would have had very little chance of finding a home. She encountered resistance within her own family (from her father, who caved in within minutes of actually meeting her adoptive daughter) and from outsiders who suggested she should be horsewhipped for expressing the wrong kind of tenderness. But although her experience had been a successful rebuke to the separatists, there was some evidence that love isn't necessarily enough in all circumstances. Another young woman recalled the loneliness of her life in Inverness, where the warmth of her adoptive family wasn't enough to offset the chill of being the odd one out.

Experiences like hers were partly responsible for the creation of the liberal racism that framed the adoption of black or mixed-race children by white parents as "cultural genocide" and lead to Swiftian absurdities, such as the mixed-race man who was turned down as an adoptive father because he wasn't "black enough". But the truth that Alagiah's programme seemed to hint at was that what the race purists had feared all along really is coming true; more and more people just don't care, and the less they do, the harder it becomes to keep bigotry in good repair. It's not over yet, but even so this was a genuinely heartening series.

Some cultural barriers have nothing to do with skin colour. Can a Scottish comedy find acceptance in English living rooms, for instance, a question being tested by Burnistoun, a sketch show from north of the border. Subtitles would occasionally be helpful, but I laughed a lot, particularly at the racehorse who took exception to a punters' insults and turned up in the back seat of his car to give him a good hoofing.