A mural by street artist Banksy on the side of a former prison which housed playwright Oscar Wilde has been defaced with red paint.The artwork, on the red brick wall of the former Reading Prison, showed an inmate escaping lockdown using a knotted spool of paper from a typewriter.It appeared on March 1 and was officially confirmed as a Banksy on March 4, when the elusive artist posted a video on his Instagram account.