I've just checked my contract that I received a couple of weeks ago and it says 28 days rising to 30 days after 10 years, but its more confusing than that it seems
Weeks of 5 turns (not necessarily of equal lengths) - 28 days leave
36 turns in 8 weeks - 25 days leave
Weeks of 4 turns (not necessarily of equal lengths) 22 days leave
I have no idea how that translates into 8 and 12 hour shifts - perhaps someone could shine some light on it!
Basically what LOM said...
A week of five turns i.e. if you regularly work five days a week e.g. Mon to Fri - so you get 28 days leave as you would expect.
The pattern I am on (8hr shifts) works out at 36 shifts worked over a eight week period (you don't count Sundays as they are overtime) - this gives you the 25 days referred to by LOM and in your contract.
Other shift patterns it depends on how many shifts per week (averaged out over the entire rotation of the full pattern) to give you your answer as per the formula in your contract.