What does the old man want that the barman does not have?

The old man would like a "pint."

"The old man whom he had followed was standing at the bar, having some kind of altercation with the barman, a large, stout, hook-nosed young man with enormous forearms. A knot of others, standing round with glasses in their hands, were watching the scene.

’I arst you civil enough, didn’t I?’ said the old man, straightening his shoulders

pugnaciously. ’You telling me you ain’t got a pint mug in the ’ole bleeding

boozer?’"