Several MPs, including Deputy Leader of the Labour Party Harriet Harman and former Health Minister Dame Tessa Jowell, joined the protest this morning.
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The kittens were in a poor condition when they were rescued, but are now putting on weight and will soon be ready for new homes.
Ian Bashford was just 200 metres from the finish line when he was struck by the car.
Cycling advocates have described the ad as appalling, and say Transport for London should instead focus on making lorries safer.