Kay wrote:
Chris Bacon writes
Your best bet is probably to do them in, somehow. Shame,
but probably most practical.

No, I'd prefer to delay the installation.

Great! As in my earlier post, when the frosts come will be OK,
they just may buzz off earlier. FWIW you may have got white-
tailed bumblebees (Bombus lucorum) - a look on Google images
will show you.