THE tercentenary of the birth of Carl Philipp Emanuel Bach (1714-88) falls this year. Johann Sebastian Bach's fifth child and second son, he became one of the most prominent of the musicians of the latter 18th century. It is often said, rightly, that his music bridges the German Baroque and Viennese Classical periods (whereas his younger brother Johann Christian, who taught the boy Mozart in London, exemplifies the new musical era).

After three decades at the Prussian court of Frederick the Great, C. P. E. Bach succeeded his godfather Telemann in the prestigious post of Kantor at the Johanneum in Hamburg, assuming responsibility for the music of five of the principal churches in the north-German Hanseatic city.

His St John Passion, first heard in 1784, 60 years after his father's famous version was first performed in Leipzig, has just been edited and performed in Christchurch Priory, Hampshire, and the Cadogan Hall, London, by the Ukrainian conductor Kirill Karabits, with the BBC Singers and the Bournemouth Symphony Orchestra.

Celebrations of C. P. E. Bach's choral output this year - the wonderfully impressive and rewarding The Last Sorrows of Our Saviour, The Israelites in the Wilderness, or Christ's Ascent into Heaven, for instance - have proved pretty sparse, although his impressive instrumental output has featured on the BBC and elsewhere (the violinist Rachel Podger will lead an attractive, all-C. P. E. lunchtime Prom in the Cadogan Hall on Monday 28 July at 1 p.m.).

Credit, therefore, to Croydon Philharmonic Choir, who celebrated C. P. E. with his bracing Magnificat (composed 1749) in Croydon Minster last November; to Ludlow Choral Society, who performed it in St Laurence's, Ludlow, during March; and to two London choirs, Highgate Choral Society and the City Chorus, who paid a similar articulate tribute to Bach's deserving son at All Hallows', Gospel Oak, with the New London Orchestra conducted by Ronald Corp, and in the Musicians' Church, St Sepulchre-without-Newgate, Holborn.

What Karabits and the BBC Singers confirmed was that, had his father and famous godfather not lived, C. P. E. Bach would still be viewed with Handel, Graun, and Keiser as a musical giant of the 18th century. He undoubtedly was then. Only the feeble historical awareness of 19th- and early-20th-century England has permitted his undue eclipse.

The Ukrainian conductor, still in his mid-thirties and now at the helm of the Bournemouth Symphony Orchestra, believes that we should not make the same mistake.

Karabits discovered the manuscript of this Passion in his home capital, Kiev, and has made of it a very performable score. In the richly rewarding acoustic of Christchurch Priory, it came across as a vibrant work. Helpful to this were the preparatory works: not just Bach's Sinfonia in B flat, vividly launched, beautifully paced by Karabits in the Adagio, and with a driven presto finale that subsided into a delightful lilt; but, even more, the Morning Song on the Celebration of Creation (Morgengesang am Schöpfungsfeste), C. P. E.'s setting of his friend the poet Friedrich Gottlieb Klopstock sublime text comparable to the theistic visions of Hölderlin ("Holy one! August one! First one! The bright Sirius of the Earth").

Its opening Adagio, with aching cellos and basses, anticipates Haydn's Creation: it bore influence: a copy surfaced among Beethoven's belongings. The whole undertaking was enriched by the singing of the BBC Singers' sopranos; when they were joined by two Baroque-sounding flutes, the effect was miraculous. Indeed "Herr! Herr! Gott! barmherzig, und gnädig" might easily have been by Haydn himself - a clear measure of how C. P. E.'s music points both forwards and backwards. This Passion dates from just two years before Mozart's The Marriage of Figaro.

A fluent and sympathetic narrator/Evangelist, Robin Tritschler, abetted by articulate cello and organ continuo, helpedlift this performance to a sublime level. The noble Christus, Michael Bundy, lent reassurance and a tangible beauty to Bach's setting of Christ's words, from his reproach to Peter at Gethsemane ("Put up thy sword") to the darkly beautiful final aria "Wenn ich keinen Trost mehr habe". When he ascends - C. P. E., as it were, abjuring his father's setting - at "Es ist vollbracht", there was an almost Schoenbergian sinister feel: compare the latter's tragic epitaph A Survivor from Warsaw.

The chorus was predictably fine: their dancing response to Pilate, "We have no king but Caesar" and the whooping "Let us not rend it but cast lots for it" were typical of their buoyant reading. Karabits's choice of pacing for "Der Gerechte stirbt fur uns Übertreter'" ("The just one dies for us misguided ones; on Golgotha Heaven is coming to rest") rendered this one of the most moving passages in the entire evening. Indeed, his expressive hands in shaping the a cappella chorales reveal him as a choral conductor of extraordinary purity, power, and intensity.

Not all of the work is original: like Handel, Bach reworked some of his own material, and here he borrows in part from his godfather Telemann. It does mean there is possibly a slight lack of dramatic thrust and cogency to the work, but this did not detract from the joy of the performance.

The Christchurch Priory Music and Arts Festival runs from 15 to 21 June, and includes a performanceof Mendelssohn's Elijah at 7.30 p.m. on Saturday 21 June.www.christchurchpriory.org

Motets by C. P. E. Bach, J. S. Bach, and Gottfried Homilius will be performed by the Collegium Singers in St Peter and St Paul, South Petherton, Somerset, on Saturday 5 July at 7.30 p.m.

www.collegiumsingers.org.uk