The ability of children to turn figments of imagination into irrefutable fact never ceases to surprise and delight. Take, for example, the four-year-old girl called Sam, in Oxford from Charlbury with parents and grandfather and enjoying a mid-morning snack in a St Giles café.

"We've been to Balamory," she told me after first introducing me to her cuddly toy dog, Mitzi.

"When?" I asked, bearing in mind the place is a fictitious village in a BBC children's television series, and filmed in Tobermory on the Isle of Mull.

"Just now," she replied, pointing along Woodstock Road.

"Don't tell stories, Sam," her mother admonished. "The man will think you are a naughty girl."

"But I did - didn't I, Grandpa?" she protested, bringing a tall distinguished man into the conversation.

"If you say so, sweetheart," he said. (Grandpas can be relied upon for support).

She then told me she had seen where various characters lived, while her parents continued to offer apologies for their daughter's over-vivid imagination.

"The houses are pink, green, blue - all sorts of colours," the child persisted. "It was Balamory - really."

Suddenly the answer became obvious. They had walked down Observatory Street, between Walton Street and Woodstock Road, where houses in the long terrace are painted in delightfully bright colours. Mum, Dad and Grandpa confessed they hadn't noticed, being intent on finding somewhere for much-needed elevenses.

"Did you see the nursery schoolteacher Miss Hoolie's greenhouse or the blue house of Edie McCredie, the bus driver? Was Pc Plum around?" I asked, displaying anorak-like knowledge acquired from grandson, a recognised Balamory boffin. Sam said she had, and feeling vindicated, was determined to press home her advantage now that someone was on her wavelength.

"Yes," she said, wide-eyed and most convincingly. "Miss Hoolie told me I could go to her house for tea."

Dozens of red balloons festooned cycle racks on both sides of Broad Street on Tuesday, each displaying the white outline of a hand. No, it wasn't an unorthodox preliminary for St George's Day, but publicity for a fashion show in Oxford Town Hall tomorrow night.

Crossing the Schools Quadrangle, I emerged into a sunny Radcliffe Square. The nodding balloon rash had spread; this time they were tied to the railings surrounding the Radcliffe Camera.

Well, almost. There was a length of about 50 yards yet to complete. Two nimble-fingered female undergraduates were doing this work, while a male student, engulfed in 50 or more balloons, dutifully passed them one by one to his companions.

The show, supported by several leading fashion houses, is in aid of Hands Up for Darfur, which highlights awareness of the tragedy taking place in that area of Sudan, where 70 children under the age of five die every day. It is working with Médecins Sans Frontières, and Kids for Kids, which devotes its work to Darfur's remote villages.

"The target is £50,000," said Hannah, a third-year psychology student at Oriel, as she leaned over the inevitable chained cycles to attach another balloon. Her companions, Maya, in her second year reading physics, and Rikin, in his first year reading maths, both at Exeter College, confirmed this hope and recommended their website for enlightened reading.

Wishing them luck for the show, I asked how they had managed to get university permission for this display of red.

"We haven't asked," confessed Hannah.

Only a hard heart could blow the whistle on such initiative and an even harder university that would have ordered the balloons' removal.

Perhaps my sense of humour is warped, but I chuckled when, on a rare foray to the Malmaison Hotel and Castle complex, I spotted the cash dispenser in the wall of the welcoming' gatehouse to the former Oxford Prison.

How many old villains would have found this a challenge too hard to resist had it been there in the old days?