Sylvia Anderson (in-universe)

When discussing whether Cloudbase was a reference to Thunderbirds or Captain Scarlet, the Twelfth Doctor claimed that he had once met Sylvia Anderson, and that "you['d] never seen a foxtrot like it". (TV: Death in Heaven)

Behind the scenes

 * Though the link isn't directly made in Death in Heaven, in the real world, Sylvia Anderson co-created both Thunderbirds and Captain Scarlet alongside her then husband, Gerry Anderson.