Of course it was a joke for days afterwards, a joke and joy to all of us

Of course it was a joke for days afterwards, a joke and joy to all of us.
(a) What does ‘it’ stand for?
(b) Why was it a joke?
© What is the antonym of ‘joy’?

(a) ‘It’ stands for the order by which Private Quelch was assigned to permanent cookhouse duties.
(b) It was a joke because the Professor’s intelligent reading and showing oil his knowledge landed him cookhouse duties instead of a commission.
© The word is ‘sorrow’.