There's something very wrong with this picture of Philip Hammond

Now here's a man who has clearly brushed up on his diplomacy and culture... ahem.

Following months of tense negotiations on Iran's nuclear capabilities, Britain's foreign secretary risked ruining the historic deal by throwing a rude hand gesture towards his Iranian counterpart.

Philip Hammond gave a double thumbs up in approval of the deal (above) but in Iran the gesture is the equivalent of giving someone the middle finger, according to Roger E Axtell’s book Gestures: The Do’s And Taboos Of Body Language Around The World.

It is a similar case in Iraq, where citizens often gave US troops the thumbs up. Whether they meant it as a symbol of support or a crass insult would be clear only to the person making the sign, which also has a pejorative meaning in Russia and Greece.

Thankfully, it seems Iran's foreign minister Mohammad Javad Zarif (far left above) turned a blind eye to the faux pas.

More: Everything you need to know about the Iran nuclear deal, in 5 bullet points