In reply to ImperialJohn:
I stand around a lot outside for work. I've used Buffalo and Rab insulated trousers. Both great but not waterproof, synthetically insulated. I'm thinking of getting some hunting trousers, the best look to be American. Very expensive. But waterproof and heavily insulated, usual used for being static. Bushcraft do a range of hunting trousers, some are insulated, only a few are waterproof too.
Paramo are a good option. But expect some water ingress if you sit on wet ground.