Classic Poem

O Digby my dear
It is perfectly clear
That my mind will be horridly vext,
If you happen to write,
By ill luck, to invite
Me to dinner on Saturday next.

For this I should sigh at
That Mrs T Wyatt
Already has booked me, o dear!
So I could not send answer
To you — " I'm your man, Sir!" —
Your loving fat friend,