Instead, they just trashed up the place. In response to this, the British government has recalled its diplomatic personnel from Iran and asked for the closing of the Iranian embassy in London. News sources say that this attack was carried out because of Great Britain ordering the cessation of all business dealings by U.K financial institutions against their Iranian counterparts, including the Iranian Central Bank.
One source I read said that this cessation of deals with the Central Bank was "much more effective than U.S. sanctions." On that point they may be correct in that it is a much more straightforward option than setting up a sanctions regime, but regardless, the pressure is mounting on Iran to stop its nuclear ambitions. Take into account the various explosions in Iran with unattributable cause, and Iran is naturally going to get more violent toward the West. However, who would expect that they still don't understand the most basic of diplomatic protocols?
All this is going to do is cause the West to take further actions against Iran, now that they have gotten their attention. What I really want to know is what does Iran have to gain from this apart from some domestic political points? The rest of the Arab world isn't likely to come quickly to Iran's aid, either because they view it as a rival regional power or are too busy with fallout from the Arab Spring. Are they trying to distract attention from Syria? Whatever the reason, the bonehead who authorized this move has not done Iran any favors.