I may be wrong here, but I suspect the events that TOFO are referring to involve a radar surface search mission off the Argentinian coast by a Nimrod, that reported that the Argentinians had sortied a small naval task group which possibly could threaten the supply lines (not that far fetched seeing that the Argentinian Air Force did attack tankers well to the north of the Falklands with Canberra's and a Hercules fitted with bomb racks on the wing tank pylons). In the end a sub was dispatched to check out the contacts which turned out to be a group of Japaneses trawlers because for some reason the Nimrod didn't attempt to do a visual check). The story is mentioned in both Woodward's book and Mike Clapp's book about the Amphibious Assault forces (which actually covers his AD plan for the AOA, and I suspect had he had the offer of a point defence by Winder equipped GR3 behind the SHAR CAP stations, he would have bitten 1 Squadron's hands off to get it).