Mark Hillkirk was a pupil at Bessie Street School and a friend of Terry Bates when Ken Barlow became deputy head there in January 1972. When watching a slideshow on the First World War that Ken presented, he told him that his own grandfather was in that conflict but go into trouble when he deliberately mis-named a Howitzer gun as a "Hows-your-father" gun and was later cheeky when Ken advised on good television programmes to watch and he replied that he'd rather watch Sylvester and Tweety-Pie. The character was not credited under his name until the April 1972 appearances onward.