That's actually super easy : obscure data sheets for embedded devices, private R&D that companies everywhere hoard, pre-internet content that nobody cares enough about to digitize, any content that rotted or was taken down by the original hosters before being mirrored, things that (dominant) search engines don't archive, things that was left behind by the SEO arms race in a priorty bucket so low it might as well not exist for any reasonable amount of effort, and etc... . Things get even worse if you consider legal questions e.g. the SciHub saga or the YouTube copyrights fiasco

I'm sure there is more if one thinks carefully enough, the internet is wonderful memory, but it's _memory_, it _will_ fail you at some point or another. Distribution merely decreases the probability of faliure, but any arbitarily small probability can be made arbitarily large by multiplying by enough population size.

Yesterday I was in the village of Broadwell, just outside Stow on the Wold, UK.

I sat on a bench which had a plaque on it. It was a memorial to Malcolm Jeffries who died on his birthday in 1974 aged 20 years. His birth day and month was not mentioned.

I felt like this was an event, something notable and I wanted to know more about it. I searched the web but so far I haven't found anything.

I'm not really challenging you, I guess I'm just saying that a lot of "knowledge" hasn't made it to the web and likely never will.

A slight aside, but are you aware of openbenches.org ?

It is a user generated database of memorial benches. It doesn't seem to include the bench you're after. If you happened to take a photo of the inscription you could add it yourself.

I'll do that, thanks.