As with all these things (and I think I use this phrase a lot so apologies if this is annoying), I think it depends on what you mean by 'left wing.' TTL UK certainly has a different class settlement and a more generous proto-welfare state but it's important not to equate that with one or more of its parties being fully fledged Keynesians. It's worth saying that OTL Keynesianism as a doctrine wasn't really worked out by 1929-30 and that's no different ITTL. Also, I've tried to make TTL's equivalent of the Great Depression, at its root, more explicitly a crisis of lender confidence and the currency (although it obviously has knock on effects for industry and employment not all that different from OTL), so it doesn't seem to politicians and bankers that this is just something which can be ridden out like 1919-21 with an increased budget deficit which will float away once growth returns. I think this explains better why some Labour figures were able to reconcile themselves to welfare cuts in an attempt to reach a balanced budget: that the crisis went to the core of the UK as a major creditor nation and the standing of the pound internationally. Hence why the paramount concern for MacDonald and Snowden in September 1930 is avoiding a devaluation of sterling (and why McKenna's and Keynes' views on the gold standard are going to become important further down the line): it's not a case of them being randomly cruel but them being stuck in a fiscal situation where deflationary tactics are the only way out they can see. Obviously, Keynes is currently a Liberal MP so query how long this orthodoxy will remain intact.