Chico and NJ are right. Although not referring to previous convictions, "similar evidence" was first admitted by the courts in the case of R v Smith in 1915 (the Brides in the Bath case). On trial for the murder of his fourth wife who had drowned in the bath, a question arose as to whether this could have occurred by natural means. The prosecution were allowed to adduce evidence that his three previous wives had drowned in the bath, which evidence, inter alia, was sufficient to send him to the gallows.