So it might benefit the UK if an air defence type radar having primary radar with the capability of providing Area services (the UK and Ireland are already makng plans for their 'funcrional airspace block) too was sited in or near near the border with the Irish Republic, although a single one could be sited somewhere like Enniskillen and that could provide coverage for most of Ireland and provide a backup for the Irish Air Defence proposal.
Surely the EU would provide funding for this, in fact the airspace extending into the Shanwick OCA is already busy enough to warrant it.
There used to be RAF radar sites at Killard and Bishops Court but I think these are long gone.