Queen bee?

Saw an enormous bee walking in the garden a few days ago, we think it is a queen Red-tailed Bumblebee. Saw it again today looking a bit lethargic in the cold so offered it a snack of honey (on a tongue-depressor, not a finger, in case you're wondering).
I sat knelt crawled around and watched its tongue sweep in and out of the honey (can just see it in the photo) for several minutes while taking photos at different angles. It continued to feed during a brief shower, then two ants joined it on the other side of the wood.
Shortly afterwards I noticed it had disappeared, I hope we see it again.