Eighty years ago yesterday, the 41-year-old Adrian Boult launched the distinguished history of what was then a 114-strong BBC Symphony Orchestra with Wagner's Flying Dutchman Overture in Portland Place. Three months later ice-and-fire Ernest Ansermet was over to conduct Stravinsky's The Rite of Spring in a programme which included the composer at the piano. Both works were indispensible to last night's celebrations: crispbread and butter wrapped around an equally representative contemporary filling that spread its wow factor relatively thin.

As experienced Wagnerian Jiří Bělohlávek came on to launch the BBCSO's new season in mid-air with the Tristan Prelude, I wondered whether the world's finest interpreter of Isolde's serving maid Brangäne, lustrous mezzo Sarah Connolly, was waiting to up her game, and her range, and tackle the Liebestod. Sadly not: that remained, as often in concert, Music Minus One. Connolly was there for a different kind of game-upping - a noble attempt to enter the charmed circle that's developed around the memory of the great Lorraine Hunt Lieberson with husband Peter Lieberson's Neruda Songs.

This season's LSO artist-in-focus, violinist Viktoria Mullova, is an incorrigible off-roader. The rougher the terrain the better. Early, modern, rock, folk: she'll absorb their shocks, vault their bumps, relish their pitfalls and come out without so much as a scratch. So Mullova's opening concert last night was intriguing. Prokofiev's Second Violin Concerto isn't exactly smooth terrain, but its roughness is pretty suburban.

People always overlook how much of a hippie Richard Wagner was intellectually. His philosophical stance differs little from that of Neil from The Young Ones. It's a side of Wagner you can't get away from in Tristan und Isolde, with its endless railing against temporal realities and its search for universal oneness - yeah man, oneness.

I suppose it was inevitable after their magnificent high with Meistersinger in the summer that Welsh National Opera’s next production in Cardiff’s Wales Millennium Centre would be a let-down. But one hardly expected a crash-landing quite as spectacular as their new Fidelio, which looks, sounds and feels like a show thrown together with a scratch cast, a weary orchestra, and a director who was shown the score for the first time last Tuesday.

I suppose it was inevitable after their magnificent high with Meistersinger in the summer that Welsh National Opera’s next production in Cardiff’s Wales Millennium Centre would be a let-down. But one hardly expected a crash-landing quite as spectacular as their new Fidelio, which looks, sounds and feels like a show thrown together with a scratch cast, a weary orchestra, and a director who was shown the score for the first time last Tuesday.

My abiding memory of the Berlin Philharmonic’s second Prom under Sir Simon Rattle on Saturday will be of 6,000 people listening with rapt, or at any rate silent, concentration to Schoenberg, Webern and Berg. Has it ever happened before?

Boy, did I want to enjoy this Prom. On paper it should have been the highlight of the season. Young Canadian conductor Yannick Nézet-Séguin has been making his mark in London as principal guest conductor of the London Philharmonic Orchestra with several sensational performances of Bruckner over the past few years. Here he was for his Proms debut at the helm of his smart new orchestra, the Rotterdam Philharmonic (Gergiev's old outfit).

In 1860 Wagner sent a full score of his recently published Tristan und Isolde to Berlioz, inscribing it: “To the great and dear composer of Roméo et Juliette, from the grateful composer of Tristan und Isolde.” The bonds between these two works go far beyond emotion, as last night’s inspired piece of programming from Simon Rattle and the Orchestra of the Age of Enlightenment proved. A phalanx of nine double basses watching over the swollen orchestral forces of the OAE set the tone for an evening whose “authenticity” was anything but dusty.

Six years after their triumphant Rhinegold, the unexpected partnership of Rattle, the OAE and Wagner have returned to the Proms, this time taking on the even greater challenge of a period Tristan – albeit only Act Two. Spanning the lovers’ move from private uncertainty to fully declared (and unwittingly public) ardour, this act has a sense of intimate detachment from the rest of the opera. Framed at the beginning and end by the receding calls of the royal hunting horns and the sudden return of King Mark, the central section sees even the faithful Brangäne melt away, leaving the two lovers alone to reach musically towards the purest expression of Wagner’s “true happiness of love”.

It’s a section that makes sense as an excerpt, but demands much from singers, denied the aid either of sets or the dramatic build-up to such intensity. Leading the way was Violeta Urmana’s Isolde, whose tone is so perfectly produced as to bypass the forceful, big clichés of Wagner singing, even in a space like the Royal Albert Hall. With a purity that sits well with this determined young heroine, she captured both the expansive lines and single-minded focus of Isolde, coming into her expressive own in the charged opening discussion with Brangäne.

It was lovely to see baroque darling Sarah Connolly, more often heard performing the likes of Handel with the OAE, making the transition along with the orchestra into this wildly different repertoire. Her Brangäne was ripe with gorgeous tone colours, particularly the Watchsong, her position at the back of the Choir lending it a dramatic potency matched only during the evening by Franz-Josef Selig’s heartbreaking “Mir dies?” – surely the most welcome of musical interruptions. Gravely noble and surprisingly well projected, his King Mark was a late star of the evening, taking the pressure off the massively over-faced and struggling Ben Heppner.

I’ve never had the pleasure of hearing Heppner in good voice, and while I’m sure accounts of his vocal and dramatic capabilities are true, the fact remains that his notoriously troubled voice is letting him down more often than not these days. When he doesn’t actually pull out of a project he frequently sounds as though he should have, and last night was no exception. It never bodes well when a tenor is cracking and straining within the first 10 minutes of Tristan, and vocal (not to mention dramatic) suicide to attempt to carry on regardless.

Carry on Heppner did, however, with a gripped tone and adolescent hope-and-a-prayer approach to top notes that simply weren’t on offer. The whole experience, far from transcendent and pure emotion, was one that left the audience nervously anticipating the next crash. Credit must go to Urmana, who staunchly continued to emote despite the intonation issues next to her, and the fact that Heppner was giving her all the dramatic impetus of a tea cosy. Heaven help next year’s Covent Garden Peter Grimes.

Translucent and flexible, the “authentic” interpretation of Rattle and the OAE was so musically convincing as to overcome its novelty. The sharper than baroque, less sharp than contemporary concert pitch of A=437 took a little getting used to, but together with German instruments brought a darker timbre to proceedings that was particularly striking after the bright French textures of the Berlioz.

I can’t help feeling that with his love of technical innovation and excess Wagner would have welcomed the greater brute force of the contemporary orchestra, but the clearly defined textures of the period interpretation made sense of his multi-layered motivic writing, drawing the eye more frequently beneath the dense surface of massed strings. And you can’t argue with the bluntly atmospheric impact of five single F horns – an absolute joy.

With his prologue of Romeo et Juliette, Rattle placed the Wagner in context both musically and texturally. Providing a different period sound for this work (using instruments made to the French model familiar to Berlioz), the orchestra showcased the expressive range of an approach that goes beyond mere academic curiosity.

With contemporary-instrument Rattle still to come at this year’s Proms, the OAE have laid down a colourful, many-textured gauntlet for the Wagner of unlikeliest of competitors, the Berlin Philharmonic.

Two birthday parties kept me away from the Albert Hall yesterday (though I'll confess that in the end I treacherously skipped the second and stayed glued to the TV's delayed relay). That, and a slight fear that the concert performance of Wagner's Die Meistersinger von Nürnberg from the BBC Proms couldn't match up to the original Welsh National Opera production of the decade.