When I worked at Arriva, bank holidays were voluntary (it was normally the same drivers each time who volunteered and got picked). You get an enhanced rate of pay plus a lieu day to take. Unsure if its the same now.

Now at GNE you may or may not be on the rota to work. It's not voluntary either. You get a slight enhancement and also a lieu day (which are just about impossible to take but if you aquire any they a lumped onto the end of your winter holidays which are also company allocated). The only time it's purely voluntary for normal services in boxing day when pay is significantly higher plus you get a lieu day.

Buses on bank holidays tend to be quite busy and the traffic is normally busy too. However with Sunday timetables come Sunday running times (vastly reduced from weekday timings). I feel an enhanced timetable would be beneficial but what routes would you pick? Also if passengers use more than one operator/mode of transport and only one has and enhanced timetable, you still have the issue of passengers not being able to complete their desired journey. Therefore for it to be appealing to the public, it would have to be an all operators and all modes enhancement.