Early on in his piece, at 07:38 on the iplayer version, the reporter Tom Heap says there are half the number of honeybees than there were in the 1960s. Honeybees specifically but no source, no authority and no geographical limits. In context, the article was about bees in the UK and that's the Countryfile broadcast area so presumably applies to the UK as a whole.
BBKA history pages say that the post war beekeeping boom had 80,000 beekeepers and 396,000 hives in 1953. The implication is that was the peak, but it doesn't say so. England and Wales only. Based on BBKA membership or an estimate overall? BBKA membership fell to 9,000 in 2001 but back to 20,000 in 2010. Is the 80,000 in 1953 all members? Could be an estimate and not comparing like with like.
Like so much reporting it's imprecise and infuriating. However, whatever the percentage BBKA membership, around ten years ago beekeeper numbers were low and could have been a quarter of the 1953 peak. Why choose 1960s when numbers were already falling, compare to now when they're rising and state the number of bees as half? Sounds more like struggling for an impressive soundbite rather than revealing what the underlying estimates actually suggest.
Might be worth asking the BBC producers where the figures are from. There was no suggestion they originated with DEFRA or it's predecessors.