The Ministry of History is a UK government ministry devoted to maintaining the flow of history at which Shelley Winters worked. The manner in which they do this (which involves the use of Nemulon units which resemble horned Viking hats but expand into "cybernetic demonoid steampunk nightmares", in Shelley's words, when a biometrically-sensed palm is placed on them; the Nemulon-9 version hasn't exploded yet) is the subject of the Destroy History webcomic strip, originally planned as one of the spinoffs of Scary Go Round in 2009 (alongside Bad Machinery and Giant Days) but not actually produced (other than two "pilot" strips) until 2015, when it appeared as a weekend strip interleaved with the current Bad Machinery story. The strip takes place in the interim period between Scary Go Round and Bad Machinery, making it approximately synchronous with Giant Days.
This agency recruited Shelley when she was seeking new employment in 2009, with Mr. Warbeck coming in person to remark on the "impeccable" quality of her resumé/CV (which she hadn't actually sent out yet). She moved to London to take this job (leaving Desmond Fishman without anybody to deal with his pooey bum), and after a one-month probational period was introduced to the agency's secrets. At that point she signed an agreement to have her memory wiped upon leaving this employment, which means that any subsequent accounts she has given (such as when she said, in Murder She Writes, that the agency was terminated two weeks after she started working there) are unreliable.
At some point she did end her employment at the ministry (under as-yet-undisclosed circumstances), and subsequently began her current career as a popular writer of children's books.