Short fat one
I sympathise with you, the MRA 4 could have been the best thing since sliced bread but SDR was about cost savings not about ability or need and any minister that says otherwise is a L***.
The E-3D is not an MPA aircraft but its paid for and can provide more than just early warning, the MRA 4 was a 3.4 billion cost saving to the bean counters nothing more.
I have had the good fortune to fly the earlier incarnations of the Nimrod and the E-3D. Yes, the E-3D can provide a good surface plot and provide an ESM input. No, it can't handle the business end of MPA i.e down in the weeds, but if you put a low cost platform out there you can handle visual ident's or with a more capable (attack) aircraft, a surface engagement. Its not perfect but its cheap and it works.
The sub surface element is a whole different ball game.
Have you looked over at Davis Montham lately? a bucketful of cheap and cheerful S-3B's are just sitting there looking for an owner. There not an MRA 4 but are fully capable MPA aircraft that would fill the gap left by the MR 2. Most of the aircraft have at least 20 years of fatigue life left on them ( if managed properly), better than a dash 8 or a caravan hunting down a warship. They possess over land targeting capability (SLAM ER equipped) as well as(on request) the full sub surface package (taken out by the US Navy)
They could be picked up for a song and provide at least a reasonable LRMPA presence for the UK.
I don't agree with the decision to cancel the MRA 4 and I certainly understand your frustration at this stupid decision however,we cannot change the minds of those that do not understand the need for such a platform.
IMHO we are moving towards long range MPA handled by UAV (as a cost saving measure) rather than manned platforms, I would not be surprised if a BAE 'idea' springs up in the very near future offering that 'one time good deal'.
Just my 2 cents worth.