In No Rest for Biggles, Corporal Penn was the radio operator on board the V.I.P. Handley Page Hastings flight piloted by Wing Commander Tony Wragg. Together with the other crew and passengers, he was taken prisoner when Christophe brought the aircraft down over the jungles of Liberia. He later met Biggles whose Hastings was also brought down by Christophe. Towards the end of the book, Penn and the other prisoners were later freed from the prison compound by Biggles, and, led by Tony Wragg, escaped to safety in Dakar using Biggles' Hastings.