What you may be seeing are drones leaving the hives on a daily basis... going to the local congregtion area waiting for the Virgin Queen to give off a pheremone signaling an unsofar never observed mating sequence, which may take several weeks. They return, if they live, each evening... in a healthy hive (at least mine here in the U.S.) there are probably around 60,000 bees and out of that maybe 100 - 500 drones. They breed with the queen about this time of year and since they're useless for anything else (like my brother-in-law) they are chased off and die soon afterwards.
Additionally, I see in certain parts of the U.K. the temperatures have been very hot this year. That leads to bees demise as well. So much so that if it continues, the bee-keeper will need to feed the hive sugar water this winter since they will not have had the opportunity or population to store up the nearly 60 pounds of honey needed for over-winter survival.
Added to that is the fact that the worker bees only live around 6 weeks or so since they literally work themselves to death (unike said brother-in-law)...
There's no evidence, by the way, that older bees are 'chased' out of the hive...