You have to be very careful if you use old compost for anything that there aren't any vine weevil grubs in it ,that's if it has had plants grown in it before. However you might mean compost that has never been used & has been in a sack in the shed for 2yrs in which case there is no problem, as far as I know. I would certainly use it

Are you talking about your old spent compost or 2 year old "new" compost from the garden centre ?.

I save all my spent compost every year and reuse it. I add growmore to it and often use it to half fill a tub then fill the rest with fresh stuff.

If the garden centre stuff...yep, again i add growmore to it as many of the nutrients would probably be gone. Got some 2 year old westland with added JI....28 litre bags for £1 each !!!

Cheers 2all