so I assume it must have existed at one point even if it's rare. At any rate, I don't see why it would be less likely to exist than any of the other three UK audiobooks.
The other reason I believe it exists is the provided image is a relatively high quality (for Amazon) scan of the cassette's J-card. The scan had to have come from kind of physical media. If it had been a low quality stock image, I would agree that it might not have existed. But it's rare for a scan of that quality to be on Amazon from that time period and not have existed. I think it's just obscure. The best thing to do would be to have an ebay.co.uk search alert for it and wait a few years until someone lists it.
Happy Holidays from Dead House doesn't have any image though.
To me the biggest evidence it exists is the image is an imperfect yet high quality scan of both sides of the J-card. Someone had to have the physical object in order to scan it, and the scan itself has scratches, crease indents and evidence of wear so it's not a stock image, or a low quality hard to read image. And it looks exactly like the A Night in Terror Tower scan. At the very minimum, at least one cassette had to exist in order for someone to scan it.
I'll admit, the fact that it's a scan is convincing.
However, according to the Keepa browser extension, the Stay Out of the Basement cassette has never been sold on Amazon UK (unless there's some kinda error). Meanwhile, Terror Tower was available from 2012 to 2014, and a listing briefly appeared in 2015.
Sorry to butt in, but I've seen this multiple times for canceled books. I've also seen this for cassettes (non-GB related). For example, I was searching for a GB book once, and I came across an Amazon listing for "Goosebumps Gold: Slappy New Year!", and "The Haunted Mask Lives", and a few other boxes sets that never existed. It's nothing new, really. About the scan...it's quite surprising. I think the cover was designed but the cassette was canceled. Now, I don't know what year this was, but I think it has something to do with Stine's fallout with Scholastic. I'm gonna try to look more into this though.
I scanned the picture's barcode, but it wasn't registered in any database as a product :(.