Just for balance………..
I received my Valedictory Certificate and letter, both signed by the Chief of the Air Staff, exactly one week after my leaving date.
Gratuity payment hit the bank on the same day – which one do you think was more welcome/useful? 
I guess Sir Glenn has to get to the office a little earlier in the day if he is signing for everyone who is leaving (and yes I did check.........not done by machine).