David Hamilton might be the oldest DJ on air in the UK at the moment but Desmond Carrington was broadcasting on Radio 2 when he was 90.
Alan Keith presented 'Your Hundred Best Tunes' on Radio 2 at the age of 94.
ABers who're interested in old time radio might like to know about ROKiT Radio, which has 16 channels available online. (The content is a mixture of British and US material):
https://rokitradio.com/
(There are detailed schedules, in either GMT or BST, as appropriate).
Pumpkin FM is similar, with 10 channels:
https://pumpkinfm.com/
(Schedules are in GMT all year round, with only the programme titles shown, rather than details of which edition will be aired).
Abacus Radio has 6 channels (plus three 'sounds of nature' streams). They include old British comedy content but there are no published schedules:
http://www.abacusradio.com/
Comedy fans will find plenty to interest them from the stations above but there also a 24-hour Goon Show channel here:
http://goons.fabcat.org/
181.FM has dozens of channels, embracing many musical genres across different eras:
https://www.181.fm/