It occured to me last night that in the absence of any official list of very early .co.uk domain registrations, the old Usenet posts would be a fine source for unearthing them since it was the main means of communication in the early days of the net and most early .co.uk registrants would have registered the domains purely for communications purposes. After all, this was before the www.
For example if we search for bt.co.uk - which is bound to be the first or one of the first domains - we should be able to see the earliest post containing that domain, so we would know the domain is at least that old, but also looking at other early posts containing that we would find other domains participating in the thread.
The trouble is that AFAIK there are just 2 main hosted dumps of the old Usenet and both have big problems when interfacing with them. Usenetarchives.com is blatantly under-resourced, if you try to search for e.g. bt.co.uk it just hangs indefinitely. You can navigate through the various groups linked on the home page (probably cached pages), but who knows which groups the domain owners would have been posting in. The Google Groups Usenet has a fast search facility but although you can order results by date it is restricted to newest first! Worse still the pagination of the results has limits preventing you from going beyond about the first 1000 results. A search for bt.co.uk yields 60792 results so you can't get anywhere near the early results. You have to add additional search terms to narrow the search down, but this will also omit many of the earliest posts that would have contained the domain but not the additional search terms.
Anyway, with a bit of trial and error I managed to unearth some very early .co.uk domains in use as early as 1986 and 1987. Of course they will have been registered before the below dates but we don't know when.
"USENET READERSHIP SUMMARY REPORT FOR AUG 86"
groups.google.com
Posted 1 Sept 1986
Mentions:
stc.co.uk
concurrent.co.uk
"UUCP map for u.gbr.1 u.gbr.2 u.grc.1"
groups.google.com
Posted 29 Apr 1987
Mentions the following:
concurrent.co.uk
datlog.co.uk
gec-erc.co.uk
hlh.co.uk
gec-rl-hrc.co.uk
stc.co.uk
inset.co.uk
ist.co.uk
latlog.co.uk
gec-mrc.co.uk
plessey.co.uk
sphinx.co.uk
root.co.uk
smb.co.uk
ssl-farn.co.uk
ssl-macc.co.uk
zen.co.uk
Of the above, hlh.co.uk, ist.co.uk and zen.co.uk have remained registered since Nominet's launch in 1996 so probably since they were originally registered around a decade before so are nearly 40 year old .co.uks!