Late Flowering Herb

In full flower since before Christmas next to my south facing front door is an upright form of the shrubby herb Rosemarinus officinalis known as 'Miss Jessop's Upright'. On sunny days it draws local flies for a winter feed.
The sun emerged today after a cloudy start and raised the temperature of this little suntrap enough to draw two Honey Bees Apis mellifera and a Buff-tailed Bumblebee.
I don't imagine nectar is produced in much volume at this time but then there can't be many active Bees in January.