You can probably blame the travel writer Peter Mayle for this, as it was he who coined the phrase 'Nice One, Cyril' for the Wonderloaf advert in 1972 (the last baker to be congratulated was called Cyril and the advert ended with the above phrase). The slogan caught on in a small way following the advert but, as Quizmonster has pointed out, took off when football fans applied it to Cyril Knowles sometime later. A chart song followed (Cockerel Chorus) and 'nice one' has been a popular expression of approval ever since.