The two vessels were originally ordered for the Imperial Iranian Navy by Mohammad Reza Pahlavi, the last Shah of Persia (or Iran) The vessels were part of an order for 4 and were similar to the Hengam and Larak (Yard Nos 1013 and 1014, delivered in 1974) However, following the overthrow of the Pahlavi Dynasty in the revolution led by the Ayatollah Ruhollah Musavi Khomeini in 1979, the delivery of the first two vessels, Lavan http://www.clydesite.co.uk/clydebuilt/viewship.asp?id=1622) and Tonb http://www.clydesite.co.uk/clydebuilt/viewship.asp?id=1622) was embargoed until 1985. They lay at Scotstoun for 5-6 years. They were eventually delivered to the Navy of the Islamic Republic of Iran. Although the keels of the third and fourth vessels were laid (the last vessels ever laid down on the open berths at Scotstoun) they were never completed. After several years they wee scrapped. In this view Lavan is the closest vessel.