Pruneface - the whole point of SAR is giving the quickest response, regardless of international boundaries - how long do you think it would take to task a UK-based aircraft (probably from Caernafon) to fly across Ireland, refuel and then go to the FV compared to tasking the Sligo aircraft to something that might technically be outside their area?
The vessel may also have been steaming towards the mainland (this is normal to reduce the range) and could well have been estimated to be inside the Irish area by the time the rendevous happened.
That aside, the Irish area really should be expanded now they have better aircraft - they would never go more than 160 nm out with the S-61 but the S92 has a far better RoA.
Gouli - are you sure about your radar theory? The minimum distance for the radar on the Sea King was 75m which is why it was so good at coastal and vessel letdowns.