I'm not sure he's even been consistent or in what way people think he "called it" on Iran TBH..
It was obvious what was coming, and you'd have to be a political clod not to realise that due to Blair/Bush the UK population had no stomach for getting involved in another US led Middle East intervention...
There was then all the talk about the USAF not being allowed to use places like Fairford for offensive ops but that changed.
Rightly or wrongly they now able to bomb up there and they very obviously use Uk airspace...compare and contrast with the likes of Spain and some other EU/NATO nations.
Another issue is the UK PM certainly doesn't appear to be prepared to be as critical of POTUS as the likes of the German chancellor has been recently.
It's almost a case of the PM keeping his head down, anything for a quiet life.