That's an interesting one. It's a right-hand-drive coach, isn't it? The guys are rather smartly dressed too. It would have been normal to stop at public toilets, but someone evidently couldn't wait. Now, who was it? We can see five guys outside the bus. The one on the extreme left, and possibly the one just to his right too, seem to have time to wander deeper into the undergrowth to hide their modesty. The one on the extreme right still wearing his jacket had time to wander a fair way forward. But the other two are standing in full view of the driver and front passenger and we can see quite forceful streams. So I'm guessing that it's one of those two who had to beg the driver to pull in anywhere because otherwise he'd wet his pants!
I reckon it's the one who's got his suit trousers undone and open. Maybe he was ripping his trousers undone as he got off the coach rather than waiting to unzip?
Yes. The stance of that guy even possibly suggests that he didn't even have time to adopt a proper standing position facing the grass but had to start peeing in mid turn. Or continue peeing in mid turn but then with proper aim!!