I read todays entry differently - perhaps im daft?
Firstly, i dont see it as jokey humour. Reads seriously to me.
Secondly, the events could be read a different way.
The young lad might have been given the money by a customer after Lea SOLD the coke, and he didnt hand it over. The shovelling could have been 3d for helping out as a casual laborer.
Or, as seems to be interpreted, he was supposed to deliver the coke, but didnt, and the shovelling tip was proof he had, as it had been shovelled.