As the article said:
The man behind Jeremy Corbyn’s most eye-catching economic policy says the Labour leadership hopeful’s plan will only work if there is another economic crisis — but adds there is almost certainly going to be one.
Richard Murphy, a prominent advocate of people’s QE, told the Financial Times the idea works only if the current government's plan fails badly. “People’s QE is necessary only if George Osborne’s plan comes off the rails pretty fast, which it almost certainly will,” he said. “There is a significant risk of another recession.”
Some predictions take less time than you expect to show signs of coming true.