I don't want to keep going on about SAR, as other people have pointed out SAR is a relatively minor, but easy to discuss openly with the public, role of any MPA. The UK has to decide what, if any, capabilities any future MPA requires. The highly specialized, complex and expensive capability of doing independent ASW, so we are talking a P-3, P-8 type aircraft, or a more limited economic zone surface surveillance type role, as fulfilled by something like a CN-235. A much more affordable option. Both types would be more than capable of undertaking SAR tasks...
However,......
As I have said before, I prefer it if people are discussing things based on facts, so I would offer the following input.
SAR is not just a "nice to have", a source of media interest, and political capital. At the end of the day, providing some form of SAR coverage out to 30W is an obligation of the UK government under international treaty, not just something we can simply decide to do or not do as required by the need to save money. I'm sure numerous governments around the world fail to fulfil obligations they have agreed to, perhaps even our own in some areas, but one would assume our politicians of all parties would want the UK to be setting a good example in order to maintain the moral high ground?