If it is such a major disaster that you need such high capacity, you are probably going to send more than one helicopter anyway.
That has certainly been a factor mentioned to me by aircrew from several territories. Has anyone seen a map for the Irish surge capacity? That would overlap UK SRR of course. The current UKSAR surge map shows levels from 3 to 7 bases within the response radius even without Irish/Dutch/Belgian/French/Norwegian overlaps. The UKSAR2G situation is similar but throws in two seasonal bases and has a different distribution of aircraft.