By 5.30pm the backstage corridors of St David’s Hall were buzzing. The 102 members of the Ysgol Greenhill orchestra, from Tenby in Pembrokeshire, had spilled out of their three allocated rooms and were eddying around wind and brass teacher Neil Martin. “Can we go out for some fresh air?” “Yes, but no more shopping in the Body Shop and don’t forget your ticket.”

There’s more to getting your school’s orchestra on stage at Schools Prom Wales than training them rigorously in musicianship and comradely discipline; you have to be parent substitute and tour guide too.

Later Ysgol Greenhill’s polished, perfectly timed performances of “The Empire Strikes Back”, “It’s About Time” (by DesmondBrubeck) and “Tequila” were among the highspots of an evening distinguished by high musical standards.

Neil Martin had special dispensation to play the tuba in the concert - the student he replaced having been obliged to go to north Wales to finish some A-level coursework - and so was wearing school uniform, much to the delight of other orchestra members (“You look 20 years younger”, said one cheekily). These 100-odd instrumentalists, some only 11-years-old, from “an ordinary comp’’ in west Wales testify to the policy of the school “to give every student the opportunity to play music that is both fun to play and educational”.

There are 1,400 on the roll at Ysgol Greenhill, drawn from a catchment area which includes country villages as well as the seaside resort itself. The school also boasts a concert band, a baroque orchestra, two choirs, six or seven string quartets, a jazz band and about four pop groups. Needless to say, an imaginative head of music, Paul Rapi, who conducts, and an “incredibly supportive” head, Chris Noble, have much to do with this. Just think, for a start, of covering for five members of staff absent for the day on chaperone duty.

But Pembrokeshire schools have another strength - they know how to work together for what they care about and have co-operated to retain their peripatetic music service which is, says Neil Martin, “the best in Wales, if not in the country”.

Members of the other six groups on the programme begin to appear backstage by 6 o’clock, as often as not clutching the remains of a McDonald’s. The Oakleigh House School, Swansea, contingent, about 60 of them, all aged between five and eight, are not milling about, however. They sit on the Green Room floor, absolutely quiet, listening to a story.

Later, their performance of How Does Your Garden Grow ? featuring pint-sized violinists and recorder players and a full cast of flowers, scarecrows, wellie-booted gardeners, sunshine, showers and a rainbow, is high on the Ah-factor scale, but there is a steely discipline behind the charm. The piece grew out of classwork in music and drama and demonstrates just how much can be expected of children when they are encouraged to pool their own ideas with their teacher’s and they have a definite goal to work to. Music is still compulsory in Welsh primary schools, incidentally, the Welsh Office having chosen to put the narrowing of the curriculum outfor consultation.

The Prom featured two living Welsh composers: Mervyn Burtch’s specially written collection of songs, Out and About, was performed with great gusto by 300 eight to 12-year-olds in massed choirs from Caerphilly and the first movement of Karl Jenkins’ Palladio was one item played by the excellent West Glamorgan Youth String Orchestra. The other two pieces in their programme were both by Vivaldi, giving full scope to their lush sound. Huw Daniel, the soloist in the concerto for violin in G minor, is (as the bilingual comp re Robin Jones reminded us) a name to watch as he leaves school on a music scholarship to Cambridge.

If there is a criticism to be made of Schools Prom Wales it is a tendency to choose “safe”, crowd-pleasing music. But, having said that, the crowd were certainly pleased, especially when offered the chance to clap along. The Wrexham Schools’ Brass Band got the proceedings underway with an amusing arrangement of “The Sun Has Got His Hat On”, with Jamie Owens playing the solo part - on tuba. John Williams’ The Lost World - Jurassic Park was suitably evocative of the experience of the film. The only group from north Wales - coach travel is expensive - they would not be home until the early hours. Good practice for their planned trip to Poland this summer.

Newport County Borough Youth Big Band set the tone for an exciting second half with “Sing, Sing Sing” and “Jumpin’ at the Woodside”. By now streamers were cascading over the stalls and intermittent Mexican waves were breaking out in the balcony. The mood was maintained by the final group, Cardiff County and Vale of Glamorgan Youth Wind Band with Beatles - Echoes of an Era and Cartoon, a sort of animated film along the lines of Tom and Jerry in sound only.

Here there was unlimited scope for adventurous percussionists who produced a range of whistles, squeaks, crashes and bangs. Christopher Marshall, who intends to be a professional percussionist, was one of those darting between drum kits. A few minutes earlier he had been one of the super-efficient stage crew. The stage manager, Adrian Evans, teaches a BTec performing arts course at Crosskeys College, Cardiff, and Christopher was among his students gaining practical experience at the Prom.

The Youth Wind Band’s conductor, composer Peter Knight, had spoken earlier of his anxiety about music funding. All areas are not as fortunate or well-organised as Pembrokeshire. Most of his musicians, aged 14 to 19 and nearly all at least Grade 8 standard, are privately trained. “I come from a background where I couldn’t have received training unless it had been free. Unfortunately, there is a huge sector missing out now.”

My guest for the evening had been Monica Roblin, head of music at nearby FitzAlan High School. After we’d all hit the roof with an emotional rendition of “Mae Hen Wlad Fy Nhadau” and the balloons had tumbled from the ceiling, she agreed that her school’s prizewinning steel band ought to have a go at being included in the National Festival of Music for Youth at the South Bank in July. Multi-ethnic Wales was not much represented at the Prom, but perhaps FitzAlan High can do something about that. After all, they won a section at last year’s National Eisteddfod - and you can’t get more Welsh than that.

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