Oh dear...we've fell out with the Iranian government,
...again.

They fell out with us more like.
Tit for tat it may be, but it's the minimal response we could do and good for Gordon Frown, I'd have kicked more than an equal two out, half a dozen at least .
It's a gesture and nought else, wooooooooo Iran recalled the Ambassadors from Britain first, before Britain banished two Iranian diplomats.
IF Britain had made the first move and expelled the Iranian diplomats first, that would be a major world statement. But as it happens...Iran rather predictably kicked out some UK diplomats....which ultimately means ...they are blaming us for the encouragement of free speech and assembly. Accuse of us outside interference, direct or indirect.
the least we can do to save wiping any egg off our face is to expel two of theirs, which as least a drastic action a government can take without looking to be backing down.