These deals are never done via an officially direct approach from the receiving government/client. There is alwatys at least one or two middlemen/trading companies in the country of origin between the OEM and the foriegn buyer. So my guess is the "U.K" company that sold the goods was first approached by a "U.K" company representing the potential buyer.
One should look into just who are the investors in the companies in the U.K. that were involved - the company that sold the devices and the trading company that brokered the deal to the Iranian government.
Great Britain has become the dominant country for Middle East financiers and investors in Europe and Iran is the sixth largest export client for Britain.
And the way this is stopped is when the people who are the middle-men begin to disappear, or have certain "accidents."
Mark