HUGE bees in my compost heap

  ...i was happily clearing out one of my compost heaps (at home) to take down to the lottie to dig in the poor areas of ground.  I heard a buzzing and saw a HUGE bumble bee (almost 1.5inches) buzzing away.....i moved out of the way for a bit to let it get its bearings and fly away, but then saw about another 10!  all HUGE.  they all seemed very disorientated and sleepy and some of them eventually took flight, but returned to the heap appearing to look for their entrance.

I have looked on the internet to see what species they are but cannot match up any of the photos.  It seemed weird to see so many huge bees in the same spot ....i have now left them alone but i am a bit worried about just how many i have (i know they are good insects) but i could really do with the compost , or if i have ruined their habitat

Does anyone have any idea what type they are and experienced this before?  They are quite long and some had orange heads and a couple black, all the same size (almost 1.5 inches) quite furry and orange stripes...although i didnt spend THAT long looking at them before a made a hasty retreat

dont worry, they can stay where they are for now ...they are too big to argue with anyway .....its just that i havent ever seen so many HUGE ones together before.....i will be keeping out of their way for now and will look again in spring to see if they are still living in there

i am away for a few days, but will report back.....although it was only when i disturbed their nest? that they started to complain....BTW,Mods....i didnt realise i now had to consider these as pets .......perhaps we should start naming them

...update....now back at home, have surveyed the compost heap and cant see any movement.  I have decided to leave well alone and hope they survive the winter and move on in the spring.  without upsetting their nest/home, i cant tell if they are still there but its not a problem as long as they are content......if anyone knows anything about these rather large species building nests, it would be nice to gain some more knowledge about them.