Tree Bumblebee or Should it be Roof Bumblebee

We have bumblebees nesting under our roof, the Tree Bumblebee.  During April and May we had the Early Bumblebee flying in and out of our roof, we could hear them in our lounge, the humming of the bees in our roof, then this last week the bees appear different, instead of being small black things with a yellow stripe and orange tails these are ginger top with white tails and they are bigger.  It seems these Tree Bumblebees have taken over the nest site in our roof and the Early Bumblebees seem to have disappeared although I do still see them in my garden.  We have a Dog Rose which we bought from the Woodland Trust about six years ago and this year it is absolutely covered in buds which are now opening up, these Tree Bumblebees love it, they don't have to fly far for their food, it's almost right underneath the roof where they are nesting.  I have read up about the Tree Bumblebee, it takes about six weeks for the queen to raise her first worker bees,  so our queen must have been in our roof raising her first young while at the same time the Early Bumblebees were nesting.  This bumblebee was first discovered in the New Forest in 2001,  it has now spread throughout England and Wales and has now reached Southern Scotland.  It is remarkable how fast they have spread and how successful they are when so many of our own are struggling.  I do find it is a privilege to have them.