The generally excellent DX Archive didn't have this info in their 'IRELAND MW ALL TIME LIST (BY FREQUENCY)
'
, saying it existed "90's - 00's"
However
a recent piece on pirate.ie (another excellent resource for Ireland) does answer my question (at least to the year):
https://pirate.ie/archive/border-series-lynsey-shelbourne-on-klas-radio/
it says UCB 549 relay finally ended in the year 2006 , which sounds correct to me.
Yes Mike it is also correct that initially, 549 was comparibly low power, before it upped power significantly at some point, and became audible (on a good car radio etc) in the far south of Ireland. But earlier than 2000 I think.
Regarding RTE on 252LW, RTE themselves wanted to 'sweep under the carpet' that areas in Northern Ireland would be affected by that closure, and portrait it as only affecting people across the Irish Sea in their own press releases to media.
