I'm now confused (easily done, as MM and FB11 amongst others can testify from their time incarcerated at Shrivenham).
NE - is your contention that it's the line put about that the Jags couldn't operate when hot that's "bo**ocks", rather than the upgrade? And that this rationale meant that JFH had to take the entire burden of the AFG task?
AIUI, the Jag could have been used, albeit with some limitations - but the fact that there was a very good chance of it making a very valuable contribution in AFG meant that it would have been terribly embarrassing for Swiss Des to have to explain why the RAF had to retire such a capable platform because the cash wasn't there to get it to its projected OSD, and even more embarassing if anyone started asking why TCH had decided to bin the whole fleet of such a useful aircraft early.
Since Des and Buff do a good enough job of embarrassing themselves without anyone else's assistance, cynics would suggest the Jag was kept out of the action for two reasons alone - to avoid making Des look even more silly and people reflecting that Hoon really was utterly out of his depth as Sec of State...
Capability and necessity? When have the beancounters in MoD ever factored that into the equation?