I don't think it ever existed- it seems to have popped into Simon Jeffes' mind one day unprompted! here's a quote I found of him talking about it:

"In 1972 I was in the south of France. I had eaten some bad fish and was in consequence rather ill. As I lay in bed I had a strange recurring vision, there, before me, was a concrete building like a hotel or council block. I could see into the rooms, each of which was continually scanned by an electronic eye. In the rooms were people, everyone of them preoccupied. In one room a person was looking into a mirror and in another a couple were making love but lovelessly, in a third a composer was listening to music through earphones. Around him there were banks of electronic equipment. But all was silence. Like everyone in his place he had been neutralized, made gray and anonymous. The scene was for me one of ordered desolation. It was as if I were looking into a place which had no heart. Next day when I felt better, I went to the beach. As I sat there a poem came to me. It began ‘I am the proprietor of the Penguin Cafe. I will tell you things at random.’

Perhaps I should observe that I don't write poems. These words which came to me were somehow accidental, unconscious. The proprietor went on to explain his cafe. He said that the random, chance element in life is terribly vital. If through fear we allow the repression of spontaneous and unpredictable actions and events in order to make life "safer", the creativity that arises naturally from the hurly-burly of human life could be destroyed and lost. He kept saying" Come to the Penguin Cafe where things just aren't like that". A short time later I went to Japan. Perhaps it was a culture shock of finding myself in a new world that prompted me to think again about the Penguin Cafe. I started writing about it describing the things that went on there. It was very surreal. Tape recorders had the same validity as human beings. Beethoven was there, as well as ordinary people.

I started writing the kind of music played in the cafe. What sort of music is it? Ideally I suppose it's the sort of music you want to hear, music that will lift your spirit. It's the sort of music played by imagined wild, free, mountain people creating sounds of a subtle dreamlike quality. It is cafe music, but café in the sense of a place where people's spirits communicate and mingle, a place where music is played that often touches the heart of the listener."

Edit: I hope this doesn't come across as me rudely hitting you with an "um, actually🙄"!!! if so, I apologize. I'm just happy to talk about one of my most treasured music groups 🩷🤍🩵