Not all hours on shift count as work, as with double manning, the 2nd person is usually doing nothing, so can be counted as POA (if both cards are in, it will be POA, )
Unless you’ve just swapped driving and are now in the passenger seat. The first 45 mins will now count as break.
Neither breaks nor POA will count towards your working time for that day.
So, if you’re salaried at £100 a day, and do 10hrs, you’re on £10hr.
Double manned doing longer runs for the same day rate, but out in total for 20hrs, means you’re on £5hr.