A saxophone and a bass guitar swing into "You Can't Hurry Love" and are soon joined by keyboard and drum-kit, bringing a touch of Motown to a February evening in south London. A couple of miles away, near the Elephant and Castle, a string ensemble starts on the Basse-Danse from Peter Warlock's Capriol Suite, in which the sound of the French Renaissance is refracted through a 20th century English sensibility. Midway between them, the languorous measures of Jacques Offenbach's plangent "Barcarolle" lead into the sexy and vigorous ebullience of the cancan. Rehearsals for the Southwark Schools Learning Partnership concert are going well.
The SSLP was set up in October 2003 by headteachers of schools in Southwark. Six of them - Geoffrey Chaucer Technology College, St Saviour's and St Olave's School, Walworth School, Kingsdale School, Archbishop Michael Ramsey Technical College, and Waverley School - are comprehensives.
Three - Dulwich College, Alleyn's School, and James Allen's Girls' School (JAGS) -are independent. Their aims are best stated on their website: "to work together to develop innovative practice... to break down barriers and increase understanding." There have already been many kinds of shared events including a Learning Enquiry conference for Year 8 students and numerous joint staff and pupil initiatives on subjects from saving modern languages to life skills and motivation.
The concert - to be held in Southwark Cathedral next Tuesday (March 28) - is a way of celebrating this and pointing to future collaboration. Dr Irene Bishop of St Saviour's speaks of how working together on music allows pupils to "unlearn prejudice and raise their game". They realise they can "be more than one kind of person". This idea was complemented by Marion Gibbs of JAGS who noted that "'looking outwards is always worth doing. If you explore your passions with other people, they become richer."
School music events can be occasions for great virtuoso displays. This concert will showcase many talents, but its essential purpose is to allow musicians with varied levels of skill to become part of a large ensemble.
The schools have divided themselves into three "trios", each comprising a pair of comprehensives and an independent. The music teachers got together at after-school meetings, miraculously finding time between Christmas festivals, exam course-work, recitals and stage shows.
Some of them were meeting for the first time and they needed to be frank about what their young musicians would be able to play and would want to play. After wishing they had more time to commission and learn a new piece, they came up with a programme that could be learnt without excessive pressure on timetables and that would sound good in a large space.
It's also a finely balanced bill of fare, with music from many eras and many countries reflecting the depth of Southwark's historic roots and its cosmopolitan present.
The Offenbach selection invites listeners back to the era of bourgeois 19th-century Parisian opera, but takes them there in the company of steel pans, marimbas and a big band. The Motown medley is joined by some gospel singing, with Aretha Franklin and Diana Ross hits backed by another group of pan players. Warlock's elegant harlequinesque masterpiece from 1926 leads into the pulsating ear-shattering street-energy of the samba (see page 22-23) - and some players are managing to perform in both.
Teachers as well as pupils have explored the benefits of collaboration.
David Adkins, music teacher at Alleyn's as well as church organist and soul singer, wrote out the Motown parts for his colleagues in the other two schools, but did so in such a way that pupils will have scope for improvisation. "Play what works," he advises Gus Lonsdale (Year 10) who is making the hi-hat swing.
Mat Fox, an inspirational samba teacher at St Saviour's, takes his skills to share with the girls at James Allen's where Gustav Holst was once head of music; in return, they will provide the lead as string players in their group.
Students find it exciting to work on music that is both familiar and unfamiliar. "The cancan is fun," says Sophie Aghatise (Year 9) who plays double second in the AMR steel band. "It's been going around the world for over 100 years and just playing it makes you smile and feel happy."
Mustafa Niyazi, a Year 11 xylophonist at Kingsdale, takes to the same piece with an observation that any music teacher would welcome: "I feel the Offenbach is not difficult, because I enjoy playing it."
Philippa Naylor from Alleyn's (Year 10) has decided views about the cathedral venue: "It's a classical space but the music will transform it."
Esther Frimpong (Year 10 St Saviour's) takes the idea further: "It would be nice if we could all play something improvised together in the concert."
That won't be possible this year, but who knows what the future may bring?
Tim Smith at AMR has put the entire Offenbach programme on the music production software Cubase. His students mainly learn by ear. He says:
"They internalise it and learn it as a whole piece, working together as an ensemble. They don't normally play classical music on pans, but it's great to take risks with a new kind of repertoire." There's a tricky CNoNo diminished chord in the "Barcarolle" and a huge rallentando that they find hard but are determined to master.
Mary Graham has run a successful music department at Kingsdale for many years and her group are all doing grade 5 theory. "They will learn the tricky bit in the "Barcarolle" from the notation and work on it at home."
Richard Owens at St Saviour's looks forward to many kinds of benefit for his students. "They will know the music from the inside, kinaesthetically as well as aurally; they will work with complex interlocking rhythms and find that watching a director becomes intuitive; they'll experience the tonal power of other players." Shakespeare (whose brother Edmund is buried in the cathedral a few feet from where the players will perform) called it "the concord of sweet sounds".
The young Southwark musicians are bringing his words to life again.
How to arrange a concert with several schools * There are many fine arrangements of well-known pieces on the internet.
Ask someone in your group to take the time to explore, you may save money and come up with some striking sounds.
* Swap mobile phone numbers and email addresses as early as possible and make sure you are all doing things that will fit together. It's very disconcerting to find that one group is practising confidently at 140 crotchets a minute and another at 110.
* If you are using steel pans, think about the balance of sound; they can overwhelm woodwind or string players. If two groups of pans are involved, check early that they are tuned to an identical physical pattern, as players often rely on muscular as well as aural memory.
* Budget for transport at an early stage, carrying vibraphones and marimbas and drum-kits needs planning and costs money.