Bert Thomas joined 'Punch' the British weekly magazine of humour and satire in 1905 and contributed until 1935. During the First World War he was in the Artist Rifles.
Thomas' political cartoons started to be included in gallery exhibitions as artistic caricatures as early as 1913, in an exhibition on the Strand by the Society of Humorous Art.
Thomas became famous for drawing also drew the cartoon of a grinning soldier lighting a pipe with the caption “’Arf a mo’ Kaiser!”. The cartoon appeared in the Weekly Dispatch in aid of the paper’s 'Tobacco-for-Troops Fund' which raised around £250,000. In 1936 his illustrations for a series of readers’ letters in the Evening News were labeled “Half a mo’ stories” and in the Second World War the cartoon reappeared with the caption “Half a mo’ Hitler”.
On October 2nd 1918, 'Punch' published a Bert Thomas cartoon depicting a boy speaking to his father, an Army officer. The boy is alluding that his Scoutmaster knows more about military tactics than his father:
Boy: "Here's my Scout-Master coming Dad. I'll introduce you. If you talk about military subjects be careful won't you? Because he's awfully clever."