Possibly the most surprising image projected for an audience at the Gibunco Gibraltar International Literary Festival showed Katherine Rundell’s study at All Souls College. Ahead of the traditional clutter of books could be seen the high — in this case quite low — wire stretched above the floor and the red stilettoes that she puts on to walk across it.

Aerial entertainment is high on the agenda for Shakespeare scholar Katherine, who six years ago became, at 21, the youngest fellow of Oxford’s most prestigious academic institution.

Besides the wire-walking, she is irresistibly drawn to the high spots of University buildings. “Through a trapdoor at All Souls you come out on to the rooftops after midnight and can see the whole of Oxford.”

These outings, and student trespassings elsewhere among the spires and domes, helped supply the inspiration for Katherine’s acclaimed children’s book Rooftoppers, which features a young girl searching for her missing mother above Victorian Paris.

The impetus to write it, and her earlier success The Girl Savage, came by strange means, as she told her audience.

One writing bout took her to the enforced isolation of a remote Scottish property, seven miles from another human being, where she had to boil snow to make coffee. “I was rescued by the army,” she admitted.

To goad herself to complete one manuscript, she wrote a cheque for an organisation she despised, the British National Party, ordering that it was to be posted if the deadline wasn’t met. The wheeze worked.