“Of all of the wild twists and turns of fate in Joe’s life,” a wry American observer messaged me earlier in the week, “St Paddy’s Day came early for Celtic.”

Former vice president Joe Biden was given the codename “Celtic” by the US Secret Service, and my contact, a person steeped in the friendships and feuds that make up Democratic politics in the US, was as surprised as anyone by the sudden heart-start to what had been Biden’s chronically flailing presidential campaign. It means there is hope for Biden, but there are always buts.