As well as getting a good idea what sort of characters I want to use, I am also getting a fairly good idea of what the plot will look like.
This isn't hard with Punch and Judy, because the basic idea is a fixed framework. Mr Punch lives in the moment, is irrepressible, does whatever he likes, which is usually whatever is under his nose, and he fancies. There are various trials, obstacles or other irritations that get in the way of a quiet life, and these are usually cause by other people's selfishness getting in the way of his own. An amusing allegory for many people's lives, hence the universal appeal. The good thing about Mr Punch is that when something gets in his way, he just bashes it out of the way, and enjoys the experience.
So the plot will be something along the lines of:
Mr Punch and Judy are at home
Mr Punch is about to enjoy breakfast
Something is preventing this
Mr Punch has to leave to sort it out and is annoyed
Judy is home alone
A trickster calls, and somehow steals the the breakfast, and possibly kidnaps Judy as well
Mr Punch returns and is even more annoyed that his breafast is thwarted
He goes off to look for it
He is attacked by a crocodile,
He fights it off, but it escapes
He is even more annoyed
Eventually he comes accross the trickster
A fight ensues, and he kills the trickster
He stops to eat the breakfast, (and may rescue Judy)
He is interrupted by the crocodile who has smelt the breakfast
A fight ensues, and Mr Punch kills the crocodile
Mr Punch is annoyed again, but at least can eat his breakfast
A policeman arrives, and prevents Mr Punch eating breakfast in a designated non-breakfast-eating area
Mr Punch gets into an argument
The policeman discovers Mr Punch has killed either the crocodile or the trickster or both
He tries to arrest Mr Punch
Mr Punch has had enough.
A fight ensues, and Mr Punch kills the policeman
Mr Punch settles to eat his breakfast, when a scientist/ecologist type official turns up and
is appalled that the crocodile has been killed.
Mr Punch denies any involvement
Scientist realises somehow it was Mr Punch.
A fight ensues, and Mr Punch kills the scientist
Eventually somehow Judy turns up
Mr Punch berates her for laziness, and demands his breakfast
Punch and Judy fight as the curtain closes...
Voila - the plot - it just needs working up!
Having got an idea of plot, I now have the characters: 
