Was listening to an interesting podcast today featuring Nigel West, discussing a new book he has written on the German Abwehr. The most interesting part was a story that apparently surfaced 2 years ago, but which seems to this point to have gone largely unnoticed.
MI5 released some documents describing a defector from the Abwehr called Otto John. John was a Lawyer, and IIRC, had some connection with the German Abwehr. After the July 20th plot failed, he fled abroad, and thence to MI6 and sanctuary in Britain. In 1950, he was appointed President of Bundesamt für Verfassungsschutz, Which I suppose was the West German equivalent of MI5. He sensationally 'defected' to the East, before fleeing back in 1955, and spent the rest of his life trying to claim he was setup by the Stasi.
https://en.wikipedia.org/wiki/Otto_John
Where it gets really interesting, the MI5 document that was released appear to indicate that by 1944, he had been an agent for MI6 for two years. Which implies that, when July 20th occurred, MI6 most likely knew it was going to happen, and that John would appear to have been a link between the Abwehr that was instrumental in the plot, and the British Intelligence service.
https://www.thesun.co.uk/news/16679322/brits-involved-in-hitler-death-plot/#
Which if its true, tends to turn the history of July 20th and WW2 on its head.
Podcast with Nigel West is here, well worth a listen.