Alumni office. Hmm, another good suggestion that I haven’t tried yet. I’ll certainly give that a try – although, as I think I mentioned, Mr Gettings if he was still alive would be something like 85 - 86 years old so it may be getting hard to find too many of his contemporaries.
That said, people do sometimes donate their papers to their alma mater? ETA: Ah it seems you gave them a try already.
Poor gentleman. I'd suspect, someone who died in these circs might be harder for you to follow up on, as loved ones may not want to speak to a researcher. You never know, though.
We used to do talks (nothing folklore/paranormal) in Skipton every year til the pandemic and I could even have subtly asked around for you, as many of those who attended were local arty types... and may well have been friends of friends or similar. Damn. We never go up there now. Or not for work.
Problem with this, Marsyas, is it's easier to do on the ground.
Have you tried:
https://www.yas.org.uk/
Also:
https://thoresby.org.uk/
Leeds archives generally are the sort you might need to be on the ground for, as well. I've worked in a number of them and indexing isn't always the best so you're less likely to find anything without physically being in the buildings where this stuff is deposited. I've spent a frightening amount of the past 15 years or so cultivating librarians and curators but that has to be done face to face.
I used to go on research trips, deliberately, with an extremely charismatic friend with an incredibly posh accent, who'd charm them to the point we could spend that extra couple of hours looking/documenting or they'd email us and invite us along. Will never forget the curator - not from Yorkshire but a neighbouring county - who beckoned us up to their library to see their latest acquisition, behind a number of alarm systems etc (since gone on display). It was a Turner. Original. Just propped against a book shelf in a backroom... Can't tell you how many trips that took to earn that level of trust! She'd schmooze them so I could just quietly work without them standing over me. It is an art and it's hard to deal with people and get their trust via email, sometimes. But in person and over time, you can get research paydirt.