Dear Mr Zuma,
Thank you for me invite to the Nelson Mandela memorial service. It is a great honour that you thought of me, although it’s no surprise that you did.
However, on this occasion I feel duty-bound to turn down yer kind and humble request. I can’t really take 100% of the credit for dismantling apartheid, although it would be fair to say I’m almost there with the ol’ poverty and what-not.