On 5 June 2017 the Avon and Somerset Constabulary announced it had opened an investigation into Banksy for the suspected corrupt practice of bribery, and the following day Banksy withdrew the offer stating "I have been warned by the Electoral Commission that the free print offer will invalidate the election result. So I regret to announce that this ill-conceived and legally dubious promotion has now been cancelled." During the COVID-19 pandemic, Banksy referenced medical advice to self-isolate by creating an artwork in his bathroom. Peter Gibson, a spokesman for Keep Britain Tidy, asserts that Banksy's work is simple vandalism, and Diane Shakespeare, an official for the same organisation, was quoted as saying: "We are concerned that Banksy's street art glorifies what is essentially vandalism." In his column for "The Guardian", satirist Charlie Brooker wrote of Banksy, "...his work looks dazzlingly clever to idiots." Banksy has also been long criticised for copying the work of Blek le Rat, who created the life-sized stencil technique in early 1980s Paris and used it to express a similar combination of political commentary and humorous imagery. Blek has praised Banksy for his contribution to urban art, but said in an interview for the documentary "Graffiti Wars" that some of Banksy's more derivative work makes him "angry", saying that "It's difficult to find a technique and style in art so when you have a style and you see someone else is taking it and reproducing it, you don't like that." Some have criticised the "obviousness" of Banksy's work and accused it of being "anarchy-lite" geared towards a middle class "hipster" audience. Much of this criticism came forward during his series of works in New York in 2013. Many New York street artists, such as TrustoCorp, criticised Banksy, and much of his work was defaced. Banksy has published several books that contain photographs of his work accompanied by his own writings:  "Banging Your Head Against a Brick Wall", "Existencilism", and "Cut It Out" were a three-part self-published series of small booklets. "Pictures of Walls" is a compilation book of pictures of the work of other graffiti artists, curated and self-published by Banksy. None of them are still in print, or were ever printed in any significant number. Banksy's "Wall and Piece" compiled large parts of the images and writings in their original three book series, with heavy editing and some new material.