In what sense? You had fairly heavily pro-austerity Tories joining Labour MPs who had left the party because - for the most part - they felt it was too left-wing. People on the centre-left/left can undoubtedly work with Tory MPs on issues where cooperation is needed and beneficial, but if you're joining an actual political party that's filled with Tories, and which is led by an ex-Tory who agrees with Tory economic policy for the most part, then how can you, in any way, claim to be left-wing or centre-left? It's fairly obvious at that point you're not. Hell, Chuka and co even had the option of defecting to the Lib Dems back in February - they instead opted to join a party filled with Tory MPs, after years of being frustrated at being called Red Tories.