If anyone else now has the Postthem Pat song stuck in their head courtesy of @CryptoFascistMadameCholet and her daughter, and would like to have the full version... here it is.
Post-them Pat, Post-them Pat
Post-them Pat and they's black and white cat
Early in the morning, just as day is dawning
They picks up all the post bags in they's van
Post-them Pat, Post-them Pat.
Post-them Pat and they's black and white cat
All the birds are singing
The day is just beginning
Pat thinks they's a very happy them
Everybody knows his bright red van
All they's friends will smile as they waves to greet them
Maybe, you can never be sure
There'll be knock
Ring
Letters through your door
Post-them Pat, Post-them Pat
Post-them Pat and they's black and white cat
All the birds are singing
The day is just beginning
Pat feels they's a really happy them
Everybody knows they's bright red van
All they's friends will smile as they waves to greet them
Maybe, you can never be sure
There'll be knock
Ring
Letters through your door
Letters through your door
(chorus repeats a bit.. Post-them Pat Post-them Pat etc.)