Gustaf Heinrich Urnst was a 25th century writer specialising in the occult. He visited what he thought was Sakkrat, but was actually Hogsumm. His memoir of his explorations there, Being an Account of my Discovery of the Unnamable Secrets of Sakkrat, was published in 2421. The Fortean Flicker on Hogsumm transported him to 1935 London. He saw the Seventh Doctor and Bernice Summerfield when they attended a play six months after he had been stranded in that timezone.
The Collected Works of Gustaf Heinrich Urnst were published in 2503. (PROSE: The Highest Science)