For 2000 people at the Barbican and a reported further 11,000 watching online, this concert of Mozart and Bruckner was a particularly special birthday party for Bernard Haitink. For the man himself, it was simply about the music. A slightly bemused smile suggested that the Dutchman was somewhat embarrassed by the fuss about his longevity – but regardless of his lifetime achievements, his Bruckner tonight was extraordinary.

Bernard Haitink conducts the LSO
© Mark Allan | Barbican

Bruckner is probably second only to Wagner in dividing opinion, but in Haitink's hands, the Fourth Symphony was realised with such convincing musicality as to warm the stoniest anti-Bruckner sentiment. While the London Symphony Orchestra was reinforced for the occasion with an additional double bass, horn, trumpet and trombone, it was the softest moments of the symphony which left the strongest mark. From the delicate hum of the opening bars, the strings played with remarkably controlled quietness despite their large number. Haitink's other main contribution was to keep tempi slow throughout the symphony, allowing its great paragraphs to reveal themselves without ever seeming forced or rushing through a passage. Such was the clarity of the work's architecture that despite the slow tempi (the whole thing came in at 73 minutes), the symphony seemed to flash past in a fraction of that time.

Of many outstanding individual contributions, those of principal horn Katy Woolley, recently elected principal with the Royal Concertgebouw Orchestra, stood out. From the terrifyingly exposed solo which begins the symphony, she played with an enormously attractive sound even at the soft dynamics encouraged by Haitink. This set the tone for an opening movement which slowly blossomed into life with all the colour and zest of an early morning walk in the spring. The birdcalls of the movement's second subject were unhurried and delicate enough to evoke Schubert. Elsewhere the brass blazed with an attractively balanced sound, and perhaps as a surrogate marker of just how well this orchestra plays for Haitink, almost every tutti fortissimo entry came off with military precision.

After standing for the whole first movement, Haitink intermittently stood and perched on his stool for the remainder of the symphony, usually standing to reinforce the heartiest passages. Elsewhere he directed with remarkable economy of gesture, just doing enough to keep the soft tread of the slow movement in step, creating the image of a moonlit procession. The Scherzo was also relatively slow, avoiding any excess of boisterousness in its horn fanfares.

The finale unfolded with an inexorable sense of destination in drawing the symphony together, the music's structure laid out with plain logic for all to hear in the journey back to E flat major. Brass roared and timpani thundered, but it was still the other-worldly delicacy of the string and woodwind playing which were most striking. The coda, growing from softly mournful trombone and horns above the gentlest string murmurs, was breathtaking.

Till Fellner, Bernard Haitink and the LSO
© Mark Allan | Barbican

The concert opened with Mozart's Piano Concerto no. 22 in E flat major. Mozart and Bruckner have become popular bedfellows in programme planning. The skillsets for each composer overlap but are still drastically different for works written in the same city less than a century apart. Haitink's approach for tonight's first-half Mozart was to stick with the 'old-fashioned' approach of modern woodwind instruments and timpani and a relatively large string section, but tempered by minimal vibrato and a punchy, muscular sound. There was some very attractive woodwind playing to admire, particularly in elegant exchanges between flute and bassoon in the second and third movements, and the velvety softness of the strings in the second supported the piano beautifully. Austrian pianist Till Fellner sparkled through the solo lines with an easy lightness of touch and deceptive sense of simplicity and no excess of showiness. It wasn't quite as revelatory as the Bruckner, but there was charm aplenty and parts of the symphony later seemed to echo the innocence of the concerto.

This was a memorable concert with the sense of having witnessed something very special. At the start of the evening, Haitink came on stage to the sort of rapturous ovation which most would very happily accept at the end of a concert; two hours later, he left to little short of a hero's send-off.