LPO/Previn/Norrington, Symphony Hall, Birmingham and Royal Festival Hall, London

Andre Previn is back. Remember that magical LSO decade, when he'd initiate us all on TV into the thrills of Ravel or Gershwin, spicing the catchiest bits with his own suave piano brilliance? Nowadays, you're as likely to find him conducting his own Tennessee Williams opera, A Streetcar Named Desire, or his new Violin Concerto (due in Boston shortly, with Anne-Sophie Mutter). And soon he steps into the great Oivin Fjelstad's (and Mariss Janson's) shoes at Oslo.

Previn is not the first Beethoven conductor to leap to mind (though he did record the piano concertos with Emanuel Ax and the RPO). But the indisposition of that Beethovenian warhorse Kurt Masur brought him to the Birmingham podium for the third in the London Philharmonic Orchestra's latest series. It was like hailing an old master; and if the orchestral sound in both Symphony Hall's razor acoustic, and in the Royal Festival Hall's enervating one in the performance four days later, seemed mixed, both halls were palpably on edge.

Scarcely had Previn gained the podium than mystery descended. The opening of Beethoven's Fourth – that wonderful lead from bassoons (consistently excellent throughout) and double basses – was electrifying; so, too, the astonishing transition Beethoven reserves for violins and timpani – here a bewitching quadruple piano – or the sublime clarinet whispers and viola judders that launch the Adagio, the mysterious tensions in the Trio (contrast the positively pastoral Trio of the Ninth), the cellos pitched high early in the Finale, the bassoon's skedaddling call to arms, or the superb envoi of the lower strings at the close.

If the Finale was a triumph, the central movements wobbled. The LPO's rather prosaic violin sound ain't a patch on the local CBSO. Tunings appeared suspect – possibly some sharpness in the seconds: a sensation never dispelled in the Seventh, despite a superb Allegretto (opening violas; oboes and flutes anon; a spectacular unison pizzicato build; and a zippy, Mendelssohnian flute solo (Celia Chambers); nor indeed a few days later, when the orchestra reverted to the South Bank under Sir Roger Norrington.

Norrington is a wonderful self-caricature. He pleads, he swivels, he teases, he lilts and joggles to gee up a trailing horn: a shoulder twitch, a bent little finger, a three-digit twiddle, a deft arch to the right, each conveys its import. With Beet-hoven's Ninth, you get the gamut: Norrington the military, the impish, the severe, the inquisitive, the scamp, the professorial and the poet.

Not all of it impacted (how often can you beam at violin desks like a benign Miss Brodie?); but much did. Bassoons (John Price and Philip Tarlton) remained pick of the bunch, along with pizzicato oboe, two vocal soloists – the wonderful Finn, Matti Salminen, and the Met's admirable Stuart Neill – and a very much on-form LPO chorus. The finale was utterly thrilling – above all, that stunning silence penetrated by bass drum, cymbal and (yes, again) bassoon. So, too, the wonderfully spare string opening to a rather thrusting Adagio. Here's hoping that Gandalf gets more buzz from them, though, in their film score for Lord of the Rings; and they'll need more of a Dresden twang for Glyndebourne's forthcoming production of Euryanthe.