I sing this one sometimes...the words are from memory, so they may be folked-up bit...

Missing
by A. A. Milne (tune available by H. Fraser-Simpson)

Has anybody seen my mouse?
I opened his box
For just a minute
Just to be sure
He was really in it...

I lifted the lid
Just to look inside...
I tried to catch him!
I tried, I tried...
He must be somewhere about the house;
Has anyone seen my mouse?

Uncle John, have you seen my mouse?
Just a small sort of mouse,
A dear little brown one
He came from the country,
He wasn't a town one

He's sure to be lonely
On a London street;
Oh where will he find
Something good to eat?
He must be somewhere - I'll ask Aunt Rose;
Have you seen a mouse with a whuffley nose?

He's somewhere about...

He just got out...

Has anyone seen my mouse?