Quinnis was a planet located in the fourth universe, (TV: "The Edge of Destruction") although the Third Doctor claimed that it was located in Galaxy Four at least on one occasion. (PROSE: The Devil Goblins from Neptune)
Settlements on the planet included Bridgetown, which was built high above the ground on a series of crisscrossing viaducts, and Fort Regal.
The First Doctor and his granddaughter Susan Foreman nearly lost their TARDIS during a visit to Quinnis the trip before their visit to London in 1963. A sudden flood carried away the TARDIS as the Doctor was posing as a rainmaker to assist the planet during a drought. It was eventually recovered by Parch's ornithopter. (TV: "The Edge of Destruction"; AUDIO: Quinnis)
The Quinnis criminal Roztoq used the TARDIS to escape to the Doctor's native universe and arrived in England in 1909, where he posed as the Marquis of Rostock until the Doctor captured him and returned him to the fourth universe. (PROSE: 64 Carlysle Street)
Whilst shopping at a market on Quinnis, the First Doctor bought Susan Foreman a seemingly dead Blitzen fish, which was kept by the Doctor in her room long after her departure. Susan wanted the fish because she liked its colour patterns. (AUDIO: Relative Dimensions)