Just over a year ago he shared a stage with Labour leader Jeremy Corbyn, Fens-based economist and tax campaigner Richard Murphy wouldn't now. He tells political editor Annabelle Dickson why.

What a difference a year makes. Last August Richard Murphy joined leadership candidate Jeremy Corbyn in addressing hundreds of supporters on the stage at the Open venue in Norwich. There will be no repeat this year.

The self-employed accountant and tax expert, who was once described as the key architect of Corbynomics, gives a damning verdict on a year of Corbyn at the helm of the Labour Party.

The tax campaigner is not a Labour Party member and only discovered that the veteran Labour backbencher wanted to use his ideas, such as people's quantitative easing, when he was invited the launch of the leader's economic policy.

Since the landslide victory, and speculation he might become an advisor, which never came to pass, he claims some approaches with suggestions have not just been rejected, they have not even elicited a response.

His own experience of dealing with the Labour leadership reflects that of many of the shadow cabinet who resigned en-masse in June.

'You go to see them [the Corbyn's leadership team], they listen to us, nothing happens. We go to the meeting, there is no agenda.'

He is also scathing of the long-serving backbencher's lack of experience of the 'nitty gritty' and turning policy into practical detail, something he claims is learnt as a shadow minister - a role Mr Corbyn never held before becoming leader. 'They have never run anything.'

'He doesn't understand the need to talk to his team, encourage them, make time for them, say thank you to them, all the other skills that come from running organisations of any sort,' he adds.

The crowdsourced questions at the flagship weekly prime ministers question session became 'predictable' and he claims to have seen first-hand how scripted Mr Corbyn had to be when he was asked to help out one week.

'His speeches are rambley, incoherent, unstructured and he doesn't know how to work an audience,' he adds.

'I can't honestly say this is the right guy to lead the Labour Party because he isn't following what I think are good economic policies, and he isn't following the ones I recommended last summer,' he adds.

But surely this is this is just sour grapes?

Mr Murphy rejects accusations from his critics that he is 'got a grump because I'm not the man in favour' and says speaking out against the Labour leader had led to a 'nasty' backlash.

'Suddenly I'm a turncoat. I am aware that as a white male I'm not going to get it as bad as the women do. I'm afraid to say women get it much worse. It is a sad thing I have to recognise that. Women have been badly treated.'

So will he give his formal backing to rival Owen Smith?

'In the circumstances, would I support Owen Smith, well yes.'

He says he is a 'quite genuinely left of centre politician' who brings with him a lot of commercial experience.

But with most of the constituency parties nominated Jeremy Corbyn, Mr Smith is not favourite to win.

So what happens for Mr Murphy next? He will continue to come up with ideas and suspects Labour politicians will continue to ask him questions. He is not a Labour member and is happy to speak to Prime Minister Theresa May if she asks.

But things have changed since the heady days of Corbyn-mania and Corbynomics last summer.

'Would I be on a platform with Jeremy this summer, no. Would I be on a platform with Owen Smith. Yes. But to talk about economic policy I believed in,' he says.