Its probably a first generation bumblebee. When a queen starts a colony at the start of a season, she has to both forage for nectar and pollen, and raise the brood. Thus the first "generation" of daughters are particularly small, as she has to work so hard, and cannot provide enough nourishment for those first few bees. Especially compared to the next generation who are reared by the "first" generation - if that makes sense?
At least, thats a possibility, but it could be Noel knows its the well known "Irish mini-bumblebee" or similar !!!
Rather than a very small bee, it could be a very large poppy. We have some (Papaver orientale - Oriental poppy IIRC) and they're comfortably 10" across.