Arriva management and Unite have played this game for years, in the end the drivers get worn down and think "Sod it we may as well accept". Rest assured if this new offer is rejected and another strike date is given, the same thing will happen again. It's 18 years since my depot had a strike and that was for only one day.
The reason there is no work to rule is that there will always be a minority of greedy drivers who will work every possible minute they can in overtime, whether they actually need the money or not. Plus it will be irrelevant soon anyway as they are flooding all the depots with new drivers on the new pitiful pay rates so they won't need to rely on drivers working overtime anymore.
