Where is he?

All we know is:

Always a very lively and interesting contributor.

I went for a quick rake through his later postings. The last model railway posting related to a new build of an O gauge layout he was just commencing in 2019, then a roughly two year sequence of showing old railway travel posters.
His last set of old travel posters concluded with 'over and out' which rather suggests to me he was 'winding down'...

Adrian said:

...Forums are strange places...

Click to expand...

Because they are novel places! In the time before internet, apart from a few radio hams you had to know more of those you communicated with, to some degree. There will be an evolution in social media customs to deal with the strangeness, but it may take a while yet to emerge.