Many thanks to SWLing Post contributor, Sam Ward, who writes:

I am looking for a nice studio version of the old Radio Prague Forward Left interval signal that they used during their communist days. I just like that interval signal very much, and I’d really love to have a nice clean copy of that famous sixties and seventies interval signal.

I know Arthur Cushen had a really nice studio version of that interval signal and I should have asked him for a copy, but we lost touch with each other, and then he passed away. What a truly amazing fellow he was.

Post readers: If you have a nice studio copy of the Radio Prague Forward Left interval signal, please comment. I would be happy to amend this post with the audio, share it with the SRAA, and make sure Sam gets a copy. Thank you!

And, Sam, you’re right: Arthur was an amazing fellow.

UPDATE 19 April 2022: Check out this post and recordings by Mike Barraclough which contain the interval signal.