The whole top-cover issue simply wan't a problem when we had a Royal Air Force that was interested in SAR and maritime aviation.
Any long-range jobs (more than 150Nm) from the Irish coast were done by RAF SAR from Valley or Chivenor or in extremis Navy SAR from Culdrose and Prestwick (RAF Sea Kings had the greater range).
Top cover was provided by the Nimrod fleet, as Jim671 has highlighted, with experienced maritime aviators, extensive comms and surveillance suite and the ability to drop liferafts and supplies.
All this went in relatively short order with the demise of the Nimrod and the contractorisation of the Mil SAR Force.
Somewhere in the change over, responsibility for the area W of Ireland was handed back to the Irish CG and Govt - if they didn't elect to provide adequate replacements then that is a matter for them.
However, having said that, it is the UK SRR (Search and Rescue Region) that extends much further West than a helicopter than reach - therefore should it not still be a UK responsibility?