There was much squirming on Radio 4 on Thursday, when British Medical Association boss Mark Porter hit the airwaves to defend the coming wave of junior doctors' strikes.

Five times, in the space of a minute, Today programme host Nick Robinson asked Dr Porter if the industrial action, which will lead to the cancellation of 125,000 operations and a million appointments, had the 'unanimous support' of the BMA's governing council, whose members had met to discuss it just a few hours earlier.

Five times, the union boss refused to answer, claiming either not to hear, or not to properly understand the question. Finally, when Robinson refused to let him off the hook, Dr Porter loftily declared that he 'will not engage' with requests to discuss what he described as 'the long and difficult debates we had inside Council'.

In the days that followed, this grumpy exchange has passed largely under the radar. But that could be about to change. For insiders say that a fractious and ugly political conflict lies at the heart of Dr Porter's strange refusal to answer this basic query.

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British Medical Association boss Mark Porter (pictured) hit the airwaves to defend the coming wave of junior doctors' strikes

It revolves around a simple fact: behind the scenes, the BMA's high command — not to mention its 168,000 members — are now deeply divided over the rights and wrongs of staging the most disruptive industrial action in the 68-year history of the NHS.

Few medics dispute that junior doctors have some legitimate grievances over the Government's efforts to impose a new contract that will (among other things) see them paid slightly less for weekend work.

Nor will you find many who doubt these highly educated and hard-working professionals deserve to be properly valued and compensated.

Yet growing numbers believe that the BMA's unprecedented decision to call for rolling five-day strikes, monthly, for the rest of the year, is disproportionate, unjustified, and risks both harming (and perhaps killing) innocent patients and alienating the public.

What's more, senior figures in the BMA believe the junior doctors' dispute is now being cynically hijacked by a hard core of far-Left activists who have quietly gained power within the organisation and are using it to advance a radical political agenda.

To this end, they say a crucial point has thus far been lost in the noise surrounding this week's announcement of the walk-out.

It is as follows: that the BMA's Junior Doctors Committee (JDC), which is at the heart of the decision to call five-day strikes, is now dominated by a cabal of Labour Party members, Jeremy Corbyn supporters, and activists with links to Left-wing campaign group Momentum and extreme fringes of the anti-capitalist movement.

Take its leader, Ellen McCourt for example, a self-styled 'Left leaning, straight talking' former orthopaedist who spent May Day on a protest march in Newcastle which had the official theme 'turn the tide against the Tories'.

Fierce industrial disputes are in her blood. Her mother Kath McCourt was chairman of the Royal College of Nursing when it threatened its own national walkout four years ago.

Take also the committee's deputy chairs. They are David Rouse, a Labour member, Aaron Borbora, a trade unionist who has spoken at meetings of the National Shop Stewards Network, and Lucy-Jane Davis, a Bristol-based Remain supporter who has used her Twitter feed to accuse the Leave lobby of 'rage and racism', and advised followers to vote Labour at the last General Election.

Other highly influential members of the committee include Yannis Gourtsoyannis, a hard-Left Marxist who has spoken alongside Jeremy Corbyn at 'fight austerity' rallies, and Pete Campbell, a Momentum supporter who wears 'Make Capitalism History' T-shirts and has used his Facebook page to promote talks in his native Newcastle on the subject of 'how capitalism is killing you'.

Then there's Kapil Ojha, a GP who uses his Twitter feed both to support Corbyn and heap personal abuse on Jeremy Hunt, dubbing the Tory Health Secretary a 'smirking idiot', an 'ignorant, arrogant waste of space', an 'idiotic dishonourable moron' who is 'cowardly, unscrupulous, ruthless and selfish'.

Also at the table is Lauren Robson, a Labour member who said last August that Corbyn was 'certainly getting my vote!', and Adam Collins, a Scottish doctor who in April shared a tweet that charmingly called Jeremy Hunt a 'c***'.

We shall look at this cabal, and their confrontational approach to industrial relations, in more detail later.

Ellen Court, (pictured) a self-styled 'Left leaning, straight talking' former orthopaedist, spent May Day on a protest march in Newcastle which had the official theme 'turn the tide against the Tories'

First, though, it should be pointed out that not everyone within the BMA, or the wider medical community, is exactly enamoured by the brand of extremist politics they espouse.

Take, for example, the Wednesday meeting that Dr Mark Porter the BMA boss has so abruptly refused to discuss.

Held at the organisation's headquarters in London's Tavistock Square, the secret meeting was attended by 40 of the 53 members of the BMA's Council, of which 28 were in the room, and another 12 took part via a video-conferencing link. Thirteen sent apologies, two blaming their absence on jury service.

It was confrontational from the start, says a witness, and at times descended into a shouting match between pro-strike members of the JDC and moderates from other sections of the organisation.

At one point, there was so much heckling that Porter, the non-voting chairman, had to appeal for calm.

Details of what exactly was said differ. According to a detailed account passed to the Mail by one attendee (who has also shown us paperwork circulated at the meeting) supporters of five-day strikes were described as 'immoral' and 'militant' by a member of the BMA's ethics committee, and accused of 'threatening behaviour' by a senior consultant.

The account states that another anti-strike official warned militant junior doctors: 'People will die. This will be blamed on us. We cannot argue it's about safety. It's about money and it always has been.'

Later, a different official is said to have argued firstly that doctors should be referred to the General Medical Council's regulator if they took part in strikes, and secondly that going on five-day strikes was 'equivalent to imposing harm on patients'.

The source claims pro-strike Council members were equally strident. For example, he alleges that a hard-line consultant on the Council urged the BMA to become more 'militant' and 'pick up where the coal miners left off' by seeking to 'break' Theresa May.

At this point, it should be stressed that others remember things differently. When contacted by the Mail, the BMA accepted that some of the quotations above were accurate, but described others as either 'false' or 'inaccurate'.

The consultant with the hard-line views also denied making the comments about aping the miners and bringing down the Government.

What no one disputes is that the pro-strike lobby intervened during Wednesday's meeting to ensure that the all-important vote on whether to back five-day strikes was taken via a public roll-call rather than a secret ballot.

'It was supposed to be a closed session, where no minutes or votes would be released,' says the attendee. 'But the militants discovered that under BMA rules, an open roll call would instead be held if five people there voted for it.

'This suited them because some opponents of strike action are afraid to make their position public in case it leads to them being subjected to abuse from the far-Left.'

Even with a public roll call, the vote to endorse strike action was far from a landslide. Indeed, only 16 of the 34 voting members of the BMA's Council supported the move. Another 11 opposed it, while seven were either absent, or abstained.

Those who were eligible to vote included Thomas Dolphin, a Labour Party member, Andrew Collier, a junior doctor elected to the Council on a ticket that endorsed turning the BMA into a 'real trade union', and Sundeep Grewal, a GP Registrar whose Facebook page describes the Health Secretary as 'Jeremy 'no one else will do this job' C**t', and whose Twitter feed in April circulated petitions calling for the 'utterly shameful' David Cameron to resign.

Like anyone else, they are, of course, perfectly entitled to hold party-political views (though you can look in vain for Conservative Party members on the BMA Council).

However, taking both an extreme position on the political spectrum, and a confrontational approach to the ongoing contract dispute, puts them at odds with many of the union's 38,000 rank-and-file junior doctors, who may also feel upset at the fact that obscenities are being levelled at Cabinet ministers via social media in their name.

To this end, it should be noted that a secret BMA document leaked to the Mail earlier this week suggests that less than a third of junior doctors (31.5 per cent) support a 'time-limited full walk-out' of the sort the organisation now proposes to undertake.

The figure was obtained from a survey carried out in June.

'On the face of this survey, the remaining 68.5 per cent of respondents would not be prepared to take part in that action,' reads the secret document, which goes on to admit that public support for junior doctors is falling while the BMA's 'member relations staff are reporting that they are not detecting the same appetite for industrial action among members [as] for previous phases of industrial action'.

Astonishingly, despite this finding, Ellen McCourt's JDC has decided not to actually ask junior doctors to vote on whether the imminent industrial action ought to go ahead.

That's because a strike ballot held last November still provides it with a legal right to call industrial action. The secret memo reveals that the committee has therefore 'decided that a new ballot should not be undertaken'.

Yannis Gourtsoyannis (pictured) has spoken alongside Jeremy Corbyn at 'fight austerity' rallies

While that decision is likely to be legally watertight, senior figures within the BMA tell me they regard it as 'ethically troublesome'.

'The original strike vote was taken ages ago, in a completely different political environment, when a different contract was on the table. Things have moved on, and many members will find it astonishing that they are now being called out on extended strikes without being asked to endorse those strikes via the ballot box,' says one.

'There is little evidence that a majority of junior doctors now support holding five-day strikes once a month.

'Apart from anything else, they will forfeit a quarter of their income. It's a mess.'

To understand how it has come to this, it's necessary to wind back the clock to 2013, when negotiations between the BMA and the Government over the new junior doctors' contracts began.

Amid growing disagreements between the two sides, several long standing members of the Junior Doctors Committee decided to step aside, finding that they could no longer cope with the demands that negotiations were placing on their time.

In their place, perhaps attracted by the colourful nature of the dispute, came a number of committee members with ties to the far-Left.

'To a degree, what has happened to the JDC is exactly the same thing that has happened to the Labour Party,' says one insider.

'Most junior doctors are what I'd call small 'c' conservatives, with fairly centrist views. But the organisation has been taken over by Left-wing radicals.'

The extent of this trend is difficult to pin down since, bizarrely, the BMA refuses to say how many people actually sit on its Junior Doctors Committee, or to name anyone aside from the committee's chairman and three deputy chairs.

However, we have identified 11 current members, believed to be the vast majority of its serving officers. Of that number, at least four are Labour Party members and three are activist supporters of Jeremy Corbyn.

One, Pete Campbell, has spent recent days using his Facebook page to attack Owen Smith, Corbyn's rival for the Labour leadership, saying he 'promises a maintenance of the status quo . . . so we should do all we can to see Jeremy Corbyn win'.

Another, Yannis Gourtsoyannis, is a regular speaker at events organised by an action group called the People's Assembly Against Austerity, who has called for a 'spring awakening' to topple the Government.

On social media he has claimed the BMA once sought to 'avoid any confrontation' but is now undergoing 'radical change' and is 'stepping up to the plate in its role as a trade union'.

A third, Lauren Robson, has attended Corbyn rallies in Bradford, describing him as 'a total breath of fresh air'.

A further five members of the JDC have either used social media to endorse the Labour Party, recently attended anti-capitalist rallies, or support Left-wing trade unions who have no obvious relevance to the medical profession.

Just two have no discernable political allegiances, although one of those two, Kitty Mohan, also has a seat on the BMA's ruling council, and spent Wednesday's meeting vigorously endorsing strike action.

The effect of their takeover has been to create a culture within the committee which celebrates and glamorises industrial action, seeking to co-opt the doctors' union into a wider anti-austerity struggle.

'It's time to dust off our picket arm-bands, an escalated fight is on,' Gourtsoyannis told junior doctors on Facebook earlier this month. 'Theresa May is about to reap what her predecessor has sown.'

Meanwhile, critics of strikes have also found themselves attacked by supporters of industrial action on social media.

The most obvious recent casualty of the increased radicalisation was Johann Malawana, the previous chairman of the Junior Doctors Committee.

In May, after five 24 and 48- hour strikes, followed by protracted talks with the Government, he successfully negotiated an amended contract that both he and the BMA called a 'good deal' for junior doctors.

However, when members were balloted the following month over whether to accept the new deal, Malawana's fellow JDC members did little to persuade them to endorse it.

Unsurprisingly, it was then rejected (by 58 per cent of participants in the vote, although low turnout meant that only represented around a third of Britain's junior doctors) and Malawana duly resigned.

Barely noticed at the time was the fact that the rejected contract also had the strong support of BMA head Dr Mark Porter, who around the time Malawana quit narrowly survived an effort by the BMA's emboldened Left-wingers to remove him from office.