A typo in the word "Netherlands" helped expose illegal Iranian weapons shipments to Yemen, the British government has revealed.
The word was spelt "Nether1ands" on part of a missile engine, in what defence officials believe was a clumsy attempt by Iran to pretend the component was Dutch.
The word "version" was also misspelt as "verslon" in one of the missile parts seized by Britain's Royal Navy last year.
In another apparent blunder, Iran failed to delete flight logs from a drone on its way to Yemen — showing it had made 22 test flights in grounds belonging to the Islamic Revolutionary Guard Corps (IRGC).
Although the drone had no great military value in itself, that it was being shipped with missile parts suggested an Iranian link to the whole cargo.
Middle East defence officials were briefed in person on the seizures by the head of Britain's armed forces, Admiral Sir Tony Radakin.
The findings have been handed to the UN as it prepares to publish a report on alleged Iranian breaches of an arms embargo on Yemen.
Iran supports Yemen's Houthi rebels, whose weapons have been used to attack the UAE and Saudi Arabia.
"Once again the Iranian regime has been exposed for its reckless proliferation of weapons and destabilising activity in the region," said Britain's Middle East minister Lord Tariq Ahmad.
"Iran’s sustained military support to the Houthis and continued violation of the arms embargo has stoked further conflict and undermined UN-led peace efforts."
The two seizures by Royal Navy vessel HMS Montrose took place in January and February last year.
Small smuggling boats were stopped in international waters after arousing suspicion by sailing unflagged at night.
The crew were Iranian citizens who were believed to be professional smugglers.
Iran at the time denied involvement and suggested the smugglers were rogue operators.
But the apparent Iranian mistakes were found after the seized items were taken to the UK for inspection.
It is believed Iran tried to cover up its arms supply to the Houthis by making equipment that appeared to come from the West.
The engine of a land-based cruise missile appeared to be modelled on a Czech design called a TJ100 but the quality and finish suggested it was a copy.
It was identified as part of a Houthi missile because of images published by the rebels themselves showing off their military capability.
Another weapon, a so-called 358 surface-to-air missile, was found broken up into components that would have been reconstructed by the Houthis.
The missile is used by the Houthis to attack drones or helicopters and is similar to a loitering missile that can roam a search area to find a target.
The welding quality was substandard and there were similarities between the missile and weapons founds in previous US raids.
But the biggest giveaway was the circuit board in the engine that claimed to be made in "The Nether1ands".
British defence officials believe this was the work of people unfamiliar with the Latin alphabet trying to imitate a Dutch product.
The seized weapons also contained parts legitimately bought from western companies, such as a French engine in the 358 missile. The drone tested in IRGC grounds was commercially available from China.
However, Britain believes Iran is seeking self-sufficiency in its arms production so that it can avoid sanctions when acquiring weapons.
"The UK is committed to upholding international law and will continue to counter Iranian activity that contravenes United Nations Security Council resolutions and threatens peace across the world," Defence Secretary Ben Wallace said.
"That is why we have a permanent Royal Navy deployment in the Gulf region, conducting vital maritime security operations and working in support of an enduring peace in Yemen."
HMS Montrose was last year replaced by British frigate HMS Lancaster as Britain's main warship in the Middle East.
Despite last year's seizures and similar raids by the US, it is believed the arms route to Yemen continues to operate, as well as drug smuggling.
Iran is also accused of breaching UN resolutions by providing drones to Russia for its onslaught on Ukraine, although those are believed to be flown directly by air.
The UN's room for manoeuvre is limited because Russia has veto rights on the Security Council.
