MUSIC: An engaging tone: Stephen Johnson on a MacMillan premiere, a Mahler First and a Tilson Thomas double act reprise from the LSO at the Barbican in London

If you were one of the great British privatised industries and wanted to commission an orchestral 'celebration', who would you get to write it? Not, surely, a Catholic / socialist / nationalist Scotsman. But BT did: they chose James MacMillan, and in Britannia they got what they deserved.

MacMillan's programme note was gently provocative. The object of celebration, he wrote, was the outstanding quality of orchestras throughout the UK (many of whom will play Britannia in the near future). But in the combination of the different British national elements, he said, 'surprising' messages might suggest themselves.

Surprising? Not for those who know their MacMillan. His vision of Britannia is a far from harmonious one. Elgar's Cockaigne, Lilibulero and a phrase from our beloved national anthem don brown shirts and march thuggishly through MacMillan's musical landscape, wrecking the moody serenity of the modal 'Celtic' sections, and at one point eliciting a protest in the form of a brief impassioned quotation from MacMillan's own The Confession of Isobel Gowdie.

But if MacMillan meant to shock, to challenge the smug London bourgeoisie, there is a problem: Britannia is also great fun - lively, bracing and in places surprisingly beautiful (there are few composers today so adept at investing tonal / modal harmonies with new meaning). After the LSO's Barbican premiere on Wednesday night, I looked around for signs of imperialist outrage, but there was only applause. That's the trouble with trying to put ideas across in non-vocal music: people will hear what they want to hear.

The conductor Michael Tilson Thomas's From the Diary of Anne Frank, written for Audrey Hepburn in support of her Unicef charity work, got round that problem by including chunks of text - Anne Frank's moving words - spoken somewhat nervously, in this case, by Debra Winger. It would be easy for an Anglo-Saxon critic to be dismissive - phrases like 'Anne Frank Goes to Hollywood' hurtle into the mind. And yet Anne Frank is beautifully crafted, and, given its remit, effective.

So, on its own terms, was Tilson Thomas's performance of Mahler's First Symphony after the interval. It was those terms themselves, not the success, that were open to question. From a balletic point of view, Tilson Thomas surpassed all his previous podium performances, and there is no doubt that he got the LSO to work hard. The heart was displayed prominently on the sleeve throughout - not in itself a bad thing; the question is, what was going on in the place where the heart ought to be? To these ears it was unremittingly sensationalist: Bernstein-like gestures without Bernstein's inner intensity. But there is a sensationalist side to Mahler. The over- fastidious might groan inwardly at the sight of the massed horns standing for the coda, bells aloft, but Mahler actually suggests this in the score. Say what you like about this performance, it certainly wasn't boring.