I heard about this '70 s UK horror TV series called BEASTS, written by Nigel Neale. I checked out the episode linked below and there are links to others (possibly all of them). Don't know about the other episodes, but this one could have easily been an old radio show. The plot was about an infestation of rats! Pretty intense, at times, considering when it was made! I'm gonna have to check out the other episodes. :)
https://youtu.be/bqxxOXkTods?list=PLbzaPhtl9x-VMmkXh55yTa_fDPNZdvpn0
Thanks for posting the link, Mike.