Christmas light

Christmas lights were a common type of Christmas decoration. The Fourth Doctor believed that Christmas lights "always end[ed] up in an impossible tangle that takes a month and most of your sanity to unpick", and he used this as an analogy to explain to Leela how the unrivalled cosmic storm known as the Great Desolatrix ripped through time and space. (PROSE: Red Planet)

Oxford Street was known for having several Christmas lights up during the season. (PROSE: Frontier Worlds) Ace rode through Oxford Street on the bus looking at the lights with her nan when she was little. (PROSE: Chemistry)

The Brigadier described the lit-up surveillance devices planted in UNIT HQ by the Master as Christmas decorations. (COMIC: The Heralds of Destruction)

The neurological trackers the Thirteenth Doctor had created for Graham, Ryan, and Yaz resembled Christmas lights. (COMIC: Holiday Special)