[KLF] Tube poster

Hi I was in Bank Tube station in London on Friday, transferring from the Northern to the Circle/District line through a seemingly never-ending series of tunnels, when I passed a poster which said, roughly speaking: "In 1994, The KLF burnt a million quid". It seemed to be part of a series of posters, possibly commemorating various historical events, presumably advertising something. Anybody else noticed it, and had the time to stop and investigate? David A