The problem as ever isn't the standards the left has to meet - it's how low the bar is for the right. Jeremy Corbyn has had a tricky encounter with Emma Barnett on Women’s Hour, in which the Labour leader was unable to remember the cost of his flagship childcare policy – for 30 hours of childcare to be made available for free regardless of parental income, benefiting 1.3 million families. The interview is great radio – you can read the transcript here but it’s better heard than read – but is it a good way to cover politics? My colleague Helen doesn’t think so, and nor does Matt Zarb-Cousin, formerly of the leader’s office, now turned pro-Corbyn commentator. They think that by asking these questions, they are turning elections into a test of memory, not an arena where the strength of the parties’ programmes are judged. Are they right? Well, sort of. As Zarb-Cousin points out, we already know that every spending commitment in Labour’s manifesto has