The bees in the perpetual hive in Headington Hill Hall park were flying at 1pm today -- 13th February.
There were flights every 3-5 seconds and I saw one bee land near me which had dark red pollen baskets. I couldn't check that she was carrying pollen but it seems the most likely. There were red Hellebores nearby which I think were probably the source of the pollen
The flowers in bloom nearby were