Many thanks for your interest. Mrs Nettlefold and I also thoroughly enjoyed that excellent theatrical tribute to Hitchcock's classic 39 Steps.
FILTHY '47 is indeed an audio project - all four parts, each of around 30-35 minutes, can be listened to or downloaded at the Podbean link above - and it's also available on other podcast platforms. (Although the ideal delivery device would of course be a crackly old valve wireless or radiogram.)
However, since it pays not to neglect the eye in this visually-oriented age, we commissioned (ourselves to produce) a promotional video in the hope that it might entice potential listeners.
If you've a substantial chunk of your life to spare (and the attention span of a Galapagos tortoise) the full-length promo - or "mega trailer" in modern parlance - is in glorious monochrome, and runs a shamefully self-indulgent 11 minutes or so: