Olympic Rings

This afternoon the Olympic rings passed by on the Thames:

















I was initially under the impression that they were being transported by water to the Olympic Park. But it would appear that these are only a set of rings, not the rings as there are various sets at different events in different places in London and other parts of the country. They set off from central London this morning, passing under Tower bridge, which was lifted specially, with Boris Johnson the mayor of London watching. Unfortunately the view I caught was of the back of the rings - they are the proper colours on the other side. Why couldn't they be painted on both sides? Apparently they will go into storage and will be seen again on the river closer to the games in 150 days' time.