Sentence:  This “volunteer laughter-maker” is looked upon in London as “the humorous success of the war”; his <WSD>"Old Bill</WSD>" and "Our Bert", and “their sand-bags, plum- and apple-jam, bully and Johnson 'oles” have become part of English war conversation. 
Meaning of the word marked with <WSD> tags:  A cartoon character created by Bruce Bairnsfather in 1914.