Instead of joining her classmates on the floor of the gym, Ruth stood on the stage and took assembly. Whilst they did their sums in class, she was handing out certificates and whilst they ran round the playground during break, she was interviewing a potential parent.

Dressed smartly in a red wool dress and black jacket - rather than her usual green uniform - Ruth was the model of dignified self-confidence as she toured the school and then decreed that £20 was to be spent on sweets as a treat for Prep School pupils to celebrate the Queen's Diamond Jubilee.

So why the sudden transformation from Year 6 pupil to head? Because Ruth had won the experience as a prize in the school's Christmas raffle.

"It's very exciting," she confided, just before being introduced as Miss Smith to more than 400 fellow pupils. "I'm a bit nervous though."

Daunting as her new responsibilities undoubtedly were, Ruth carried off her new role with aplomb.

"She played the part remarkably well," said Caroline Pascoe, Truro High's real headmistress. "I can see I'll have to watch my back or she'll be taking over permanently!"

Ruth's moment of glory, however, lasted until just after lunch when she rejoined her friends and, a little more relaxed, went back to lessons.

Ends 1 June 2012

Photo (by Bernie Pettersen) : Caroline Pascoe puts Ruth's name on the head's door

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