According to a documentary broadcast on BBC Radio 4 last night, the French cheated on us during the Falklands War by helping the Argies while they were pretending to help us.

No one is suggesting that President Mitterand was anything other than wholehearted in his support for the UK. He ordered an immediate and complete embargo on supplying or assisting the Argentines. Vital technical data on the French-made anti-ship Exocet missile was made available to the Ministry of Defence, the French having sold five to the Argentines before the war.

French intelligence supplied leads to MI6 as it tried to prevent Argentine emissaries from buying further Exocets on the black market and turned a blind eye as British spooks carried out covert sting operations on French soil. The Fleet Air Arm was even able to practice against the same French-made Mirage aircraft operated by the Argentine Air Force, while the French Navy made its repair and resupply facilities at Dakar in Senegal available to our Task Force.

But at the same time, according to convincing evidence unearthed by the BBC, a group of French technicians in Argentina fine-tuned and repaired the five air-launched Exocet missiles the Argentinians had already purchased.

It was the most potent weapon in their armoury. Carrying a 165 kg warhead and skimming at high speed one to two metres above the sea it usually only showed up on the radar a few seconds before impact. The codeword for an incoming Exocet attack on the ship's tannoy "Handbrake, handbrake, handbrake. Brace, brace, brace" was the most dreaded broadcast of all.  

One of those missiles hit HMS Sheffield on 4 May (20 British dead). Another hit the supply ship Atlantic Conveyor on 25 May (12 British dead).  Famously, Prince Andrew was one of the helicopter pilots flying decoy missions that night in an effort to confuse Argentine targeting.

Two more were launched against HMS Glamorgan (13 British dead) on 12 June, as she gave naval gunfire support to Royal Marines fighting ashore. On this occasion it could have been much worse - the first missile failed to find its target and the second was rendered less effective by a last-minute turn to starboard at 24 knots by Glamorgan's on-the-ball navigating officer, saving the ship from catastrophic damage.

It is clear from the BBC's investigations that most of these missiles would have been duds without the efforts of the French technical team. What is less clear is the extent of the involvement of the French state.  

Mitterand's embargo was ordered in good faith and generally observed - with the exception of the Exocet specialists already in Argentina and employed by the missile's manufacturer. One French official interviewed on the programme furiously called their actions "treason".  But a senior ex-spook also admitted that one of the technicians was an agent of the DGSE (Direction Générale de la Sécurité  Extérieure), France's MI6.    

Sir John Nott, defence secretary at the time, also confessed to knowing about the team. Interviewed for the documentary, he protested half-heartedly about French "duplicity" but signally failed to get hot under the collar. The key point in his view was that the French helped us prevent the Argentines getting their hands on any more Exocet missiles.

French support for us may not have been "picture-perfect" but the overall effect of the programme was to highlight how generally effective it had been. Certainly streets ahead of some of our other "allies".  

The Belgians, for instance, refused to sell us artillery and small arms ammunition.

Israel's extensive support for Argentina during the war was laid out recently in startling detail by the Argentine journalist Hernan Dobry in his book Operation Israel: the Rearming of Argentina During the Dictatorship 1976-1983. Menachem Begin, then prime minister, did all he could to transport arms and equipment to Argentina because he hated the British so much. Apparently, in 1947 the British Mandatory authorities had (after due process and quite properly) hanged one of his terrorist chums.

But it's the attitude of the United States that still grates most of all. Their reluctance to support us against the Fascist Argentine Junta is well known. Initially, in April 1982, they even refused us permission to use the US operated airfield on Ascension Island (a British Crown Colony for Heaven's sake) to refuel RAF aircraft.  In 2012 the US does not recognise our legal claim to the Falkland Islands which Hillary Clinton's staff insolently refer to as "Las Malvinas".    

The next time the Americans want our support in a military venture (and, yes, there seems to be a big one in the offing) we should tell them to take a hike.

BBC Finds Evidence That French Helped Argentines Sink Our Ships