Paddy Brennan was one of D.C. Thomson's most popular illustrators of adventure comics, mostly for magazines like Dandy, Topper, Beezer and Judy. Brennan had his first publication in the one-off Magno Comic in 1946, published by International Publications in Glasgow. He worked for several other minor publishers, until he began working for D.C. Thomson in 1949.
For over 40 years, Brennan contributed to many of the publisher's titles, initially mainly for Dandy and Beano, as well as People's Journal. He started out doing "Arabian Nights" stories like 'Sindbad the Sailor' (Beano) and 'Ali Baba and the Forty Thieves' (People's Journal), and a half-page comic strip called 'Rusty' in Dandy.
From 1951, Brennan became one of the most prominent illustrators of adventure stories, resurrecting Dudley Watkins series like 'Jack Flash and the Terrible Twins', 'The Shipwrecked Circus' and 'Young Drake'. In the following decades, he produced dozens of stories in varying genres, like historic ('The Galloping Glory Boys'), sea, and western ('Crackaway Jack').
From 1953, he was also present in Thomson's tabloid-sized comic Topper, doing the single-page strip 'Flip McCoy - the Flying Boy' and some novel adaptations, like Sabatini's 'Captain Blood' and H. Rider Haggard's 'The White Witch'. His longest running strip for this magazine was 'The Whizzers from Ozz', which started in 1966 and appeared throughout 1967.
By 1958, he went to work for the girls' titles Bunty and Judy, doing mainly literary adaptations and stories like 'Sandra of the Secret Ballet'. For the Beezer, his most notable work was 'The Showboat Circus'. Brennan continued to work for the company during the 1970s and 1980s, working for his main titles, but also the new Cracker, for which he made 'Iron Hand'.