bumblebees

Observation - bumblebees - UK and Ireland. Description: on the grassy track of a small wood/plantation in shillingford st george near exeter on hot early afternoon semi shade. two bumlebees lying abdomentip against abdomentip on their side (mating?) what puzzled me was that one was large black with ginger red

on the grassy track of a small wood/plantation in shillingford st george near exeter on hot early afternoon semi shade. two bumlebees lying abdomentip against abdomentip on their side (mating?) what puzzled me was that one was large black with ginger red tip the other half of the former's size and with a cream stripe as well as aginger tip.Would like confirmationas to species and behaviour