I met a man who wasn't there

For some strange reason I'm not included in the register for the Context of Practice course, which prompted me to (mis) quote this poem this morning:

Yesterday, upon the stair,

I met a man who wasn't there.

He wasn't there again today,

I wish, I wish he'd go away...

When I came home last night at three,

The man was waiting there for me

But when I looked around the hall,

I couldn't see him there at all!

Go away, go away, don't you come back any more!

Go away, go away, and please don't slam the door...

Last night I saw upon the stair,

A little man who wasn't there,

He wasn't there again today

Oh, how I wish he'd go away...