Jack Jarvis is played by Ford Kiernan. He is a stout, squat man with white hair (though it was once ginger) and a moustache. He can frequently be seen wearing a bunnet when outdoors and smoking a pipe. In his younger days, he worked in his father's grocery shop and was an amateur boxer. He has been best friends with his neighbour Victor for over sixty years, both living on the same floor of Osprey Heights, a tower block in Craiglang. The two first met when a young boy named Frank McCallum was knocked down by a tram. Jack is a widower and occasionally struggles with loneliness as his wife, Jean, died in 1991 and their daughter Fiona has emigrated to Canada. Jack spends almost all of his time with Victor, most frequently at their local pub, The Clansman. In contrast to Victor, Jack demonstrates slightly lower intelligence, a higher chance of being swayed by peer pressure from others, and less of a way with words (often trying to be witty but instead only producing a banal remark, and using malapropisms - such as saying "discretion" instead of "desecration"). Additionally, he seems to be more easily offended and quick to anger than Victor. However, Jack has shown himself to be more observant than Victor on several occasions; notably, in the episode "Wummin", he recognises (albeit incorrectly) that Bert Findlay's strange behaviour shows signs of an impending
suicide.
In the first episode, "Flittin'," Jack is said to be 74 years old (the same age as Victor), confusingly, in all other episodes his age is stated as 72. In a sketch on the sister programme Chewin' the Fat, his surname was given as McAlpine.