This was found by discord user Storyfan134. If there is anyone to thank, its him.
The sighting comes from Ghosts and More Ghosts, which is a collection of short stories. The inflation scene is found in The Wonderful Day.
To sum it up, the inflated is a full bodied female with an ego and is fashionable. Basically, a 1950's model becomes a full balloon.
This was published before Charlie and the Chocolate by 1 year.
https://sta.sh/21ta95d8v2wp?edit=1
I know there will be some spelling errors XD i am sending this all from my phone and on no sleep.