It was definitely illustrated by Quentin Blake but I don't remember if he wrote it.
As far as I recall, It was about a very messy attic getting fuller and fuller and characters in it trying to tidy up and finding stuff like a big rug and a chest.
It was written in rhyming coupletsremembers remember. It ended in some sort of big bang and the whole attic was suddenly tidy.
I loved this book but can't remember what it's called.
Can anyone help?