[Robert Williams]

Devon and Cornwall were two of the last stations to launch, I think there is just Radio York and a couple of others (plus the likes of Somerset that started out as a part time opt out) that haven't made it to 40 yet.  The oldest stations in the network are 15 years or so older.

There's a fair few stations that launched after 1983 - not counting relaunches and rebrands, there's Bedfordshire (1985 - became 3CR in 1993), Shropshire (1985), Essex (1986), Somerset (1988), Gloucestershire (1988), Hereford and Worcester (1989), Wiltshire (1989), CWR (1990), Suffolk (1990), Surrey (1991), Berkshire (1992) and Dorset (1993 - became part of Solent in 1996).

EDIT - apologies, hadn't seen the post above when I typed this!

The whole Surrey/Sussex/Brighton thing was rebranded as a single station called Southern Counties for a while, still with split programming at times.

This is probably my specialist subject!  Radio Surrey launched in 1991 as an opt-out of Radio Sussex for seven hours a day as a cost-saving measure (likewise Berkshire launching shortly afterwards as an opt-out of Oxford), but barely two years later was merged with Sussex with split programming gradually reduced to nothing over a period of six months, leaving a fully merged station at the start of 1994 called Radio Sussex and Surrey - this was rebranded as Southern Counties Radio the following August.  The schedule was made-up entirely of programmes that were four hours long (sound familiar?), music was no longer played, and there was no split programming whatsoever.

It was on the next major relaunch on 1st Sep 1997 that music was reintroduced, and three separate breakfast shows for Surrey/Sussex/Brighton were introduced, along with split news bulletins.  And, other than the demise of the Brighton breakfast show in 2006, and despite the reintroduction of the separate Surrey/Sussex branding in 2009, that's pretty much where we still are today - although these days it seems pretty hit and miss as to whether any given news bulletin is actually split between the counties or not.

Berkshire, meanwhile, had different fortunes, gaining its own full schedule at the end of 1992, but then merging with Oxford in 1996 to form Thames Valley FM.  With this merger deemed unsuccessful, they regained their own identities in 2000 but still with some joint programming, eventually becoming standalone stations once more by 2004.