IOC chiefs 'make secret plea' to use London 2012 venues as Rio 2016 Olympic Games fall behind schedule - Telegraph: A source told the Standard: "At a comparable planning stage in 2004 Athens had done 40 per cent of preparations on infrastructure, stadiums and so on. London had done 60 per cent. Brazil has done 10 per cent - and they have just two years left. So the IOC is thinking, 'What's our plan B?'
"Obviously, the answer would be to come back to London. It's very unlikely but it would be the logical thing to do."
London has hosted the Olympics in an emergency before. In 1908 the event was due to be held in Italy, but Mount Vesuvius erupting forced a move.