The 1958 BBC serial Quatermass and the Pit has a very Lovecraftian plot. From Wikipedia:
Quatermass and his new colleague Colonel Breen become involved in the discovery of a bizarre object at an archaeological dig in Knightsbridge, London. As the serial progresses, Quatermass and his associates find that the contents of the object have a horrific influence over many of those who come into contact with it. As this influence increases, affecting Quatermass himself, darker implications are revealed about the entire nature and origins of mankind.
The serial has been cited as an influence on the writer Stephen King and the film director John Carpenter. It featured in a list of the 100 Greatest British Television Programmes compiled by the British Film Institute in 2000, where it was described as “completely gripping”, and in 2005 the BBC’s own website declared it “simply the first finest thing the BBC ever made. It justifies licence fees to this day.”
Watch it below! (And you can also watch Quatermass 2, here.)