Just to put the record straight, it was only G-BFMY that went to Rio Grande, the picture of G-BFRI was taken at Mount Pleasant Airfield in the Falkland Islands. The bearded fellow in the photograph was an Argentine engineer called Oscar, and not David Mallock. Despite all appropriate diplomatic clearances apparently being in place, the aircraft was impounded for five days on arrival, it being the first commercial flight from the Falklands to Argentina since the 'conflict' in 1982. All the Argentines in the photograph had served in the military in 1982, but despite that were a very pleasant bunch of people to work with.
At the end of the contract MY was flown back to the Falklands, and shipped back to the UK with RI. Ferry tanks consisted of 45 gallon drums, and a hand pump to transfer the fuel to the centre tank - wouldn't be allowed these days I'm sure!