After-school brass band practice at St Giles junior school and headteacher Bob Jelley comes in late with his euphonium. Nine-year-old Lauren, who plays the same instrument, points out the place in the score, without missing a beat, in time-honoured style, and Mr Jelley joins in.
The euphonium - mildly assertive in a supportive sort of way, yet satisfyingly cuddly to hold - is surely the ideal instrument for a primary head. So when Maurice Greaves, volunteer community brass band tutor at St Giles, in Exhall, north Warwickshire, conjured up a tired looking but serviceable example (Maurice seems to have a magical talent for finding instruments) the right person to play it was obviously the head, Bob Jelley.
Bob started from scratch a year ago By December he had progressed to the point where he was able to undertake a demanding tour with Maurice's adult band. (OK, it was round the local housing estate playing carols, but the achievement is considerable nevertheless.) Learning a new skill alongside your pupils is one of those things that every teacher ought to do at least once in a career.
"I sit beside Lauren," says Bob. "She's nine, and she's steady and entirely fearless."
A bit cheeky, too. "Here's a cliff, Lauren," said Mr Jelley after one bit of badinage,"and here's you, teetering on the edge of it."
She's as good as him, too, even though he reckons he practises more.
"I can carry my instrument home more easily than she can," he says. There are differences, he adds, between the way adults and children approach rehearsal.
"Adults aren't silly between pieces. The children hide each other's mouthpieces and so on. And they forget their music. You need six copies of everything, and all six will still vanish."
As many instrument-playing readers will testify, Mr Jelley here demonstrates the narrowness of his experience in the ways of adult musicians. Maybe at the London Symphony Orchestra the players don't lose music and wind each other up, but there are adult ensembles where, shall we say, it is not unknown.
On the plus side is Bob Jelley's delight in seeing children make big strides in achievement.
"There are these quantum leaps. One minute the children are saying that something is too hard and then suddenly it all comes together and they start to want to play it again."
His own enthusiasm stands up well to the remarks of his fellow pupils.
"Your face went all red, Sir, and water started coming out of your eyes," said an awestuck cornettist at one point.
At the end of the rehearsal, though, came a reminder of the realities of life for a primary head as Bob stood with the tailgate of his estate car up loading in the instruments and bags of the players he was taking home. Many children, he points out, would be shut off from such activities if they didn't get lifts.
"One girl told me today she'll have to leave the band because it's more difficult now for her mum to pick her up. I'm going to have to see what we can do."