There are certain songs which are hits at the time and stay hits, and others which are typical of their time and yet somehow point towards the future; I can't say I knew this song before I heard it (it is yet another step in my understanding UK culture) and it is a song that seems to look back to the wide-eyed, expectant time before The Beatles and ahead to something quite different.
The narrator is eager, willing something to happen, even if it's just in her imagination and she knows nothing will really happen. Yet, when she closes her eyes, she gets the "strangest feeling" - a feeling that may be instinct, may be pleasant or unpleasant, though with Hopkin's voice it of course sounds as if it could only be a good thing, and she certainly sounds welcoming enough. (The song's writers, Geoff Stephens and John Carter, are the guys in tuxes in the back, as was the custom at Eurovision at the time.) John Carter's own demo of the song points up the fact that maybe the teardrop on the window and the strangest feeling are more disturbing and that to imagine someone knocking on the door is, come to think of it, kind of delusional. No one just knocks on a front door and steps in unless the person inside has invited them somehow; even if what the narrator is inviting in is an abstract - Love - well, that is equally odd, as Love rarely responds to such passiveness...
...so what is going to come in, what is really awaited? An actual person, romance, Love? The 70s themselves could be in this room already, with Hopkin as its voice, and her tremendous eagerness for something, anything to happen is as hopeful and naive as the new decade itself. Who knows what is going to happen? That something will comes through in the music, all curlicues and confident, swooping like a bird from note to note.
This same room will occur again (I know I've mentioned it before in conjunction with Hopkin, but this time it's even more pertinent) in 1977, a room where her voice comes back as that welcoming spirit to perhaps comfort a man who cannot leave his room, who is scared of what is outside and yet is waiting; waiting for a gift that is mysterious, one which doesn't come from a knock on the door but from the inside, from a place where that strange feeling starts. Hopkin longs for Love to come and relieve her from solitude, but here solitude is required, it seems, for anything to happen at all. That Hopkin is there may also point back to the optimistic delusion of this song, and Bowie sings more to himself, when he bothers to sing at all.
"Knock Knock Who's There?" got second place at Eurovision (as it does here) and for all I know it may have been some influence on Bowie at the time; it sounds like a much simpler and happier song than it really is. This is not a new thing in pop, but it will start to happen more frequently as something that is for now nameless begins to find its roots and slowly begins to grow, with Stephens and Carter two of its friendly forebears. The 70s has more of them in store, as pop begins to grow in two distinct ways - the dull and predictable, and the strange and lovely. This song belongs to the latter, all black and sparkling, contradictory and yet united.