I certainly would have mobilised in the middle East.
It's called sabre rattling.
Just because you mobilise, doesn't mean you actually have to fire the first shot.
But for what purpose? Any mobilisation's cost would far outweigh any gains, not to mention that the British armed forces are already massively overstretched in Iraq, Afghanistan and other deployments. Any further commitment of forces risks overstretching the services further and undermining an already poorly supplied bunch of men and women in existing theatres. To merely 'sabre rattle', that's a hugely expensive and risky operation.
I take your point on their massive army, but I'm pretty sure our weaponary and fire-power is FAR superior to theirs.
But as Iraq has shown, that might win you a battle or two, it certainly doesn't win you a war and risks tying yourselves down for years. Iran has the eighth largest army in the world against the UK's 20th and as someone else pointed out, they're on home soil without any other commitments. However well-trained our army is, you risk the deaths of thousands if you support military action in this case.
To cap it all, they force her to wear an islamic, (note no capital 'I'), head-dress.
That's less a political point and more bad grammar, JR....