There are some traditional toys and games no child should ever go without, says Tom Karen, a 95-year-old toymaker who lives in Cambridge, “like loveable dolls, soft toys, Lego, Monopoly, Connect Four – and yes, the Marble Run.” Karen invented the Marble Run in the 1960s after noticing how his own children found marbles thrilling. “I was surprised how much pleasure they got from a fixed run where all you could do was feed marbles at the top and watch them zig zag their way down,” he says. “It occurred to me, if a marble run could be constructed in different ways it would provide a creative challenge, with a very pleasing reward – it would make a hugely satisfying toy.”