Like most earthquakes it began with barely a rumble along a fault line, before the very public explosions and outpourings. At the start of this month the impressive SNP MP Joanna Cherry had been given police protection over death threats and online abuse on social media. Last Sunday this newspaper revealed that she was at the centre of a bullying inquiry into alleged staff mistreatment inside her own office.

The SNP has long maintained an impressive outward solidarity but this tremor, the shifting of the party’s internal tectonic plates, has badly shaken it. The reaction has been extreme with on and off the record briefings and sniping at the Herald on Sunday.

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Cherry strongly denies the bullying allegations, claiming that she is the victim of “politically-motivated smears” and “back stabbing” by rivals within party, quipping sarcastically that even the Tories act more honourably by wielding the knife in public. She even appeared to rebuff an olive branch from Nicola Sturgeon who had described her as a “massive asset” to the party, stopping short of a wholehearted endorsement of her innocence.

Last Sunday’s Herald on Sunday exclusive by Hannah Rodger revealed that former case worker Iona Paton accused her of hypocrisy. “I couldn’t stay silent any more when she started saying she was the victim of bullying when she knew she was dealing with all these complaints of bullying against her and [office manager] Fraser [Thompson].

Four former staffers in Cherry’s constituency office have now made complaints which are being considered by Commons officials. A former election agent has also quit the party over what he claims are personal differences with the Edinburgh South MP.

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The abuse Cherry faced came when, at an evidence session of the Commons Joint Committee on Human Rights, she questioned representatives of Twitter and Facebook about the online abuse of female MPs. Following that she was deluged with offensive tweets and threats, one message included a cartoon with a gun with the words “Do it”.

There was also a message which confirmed Cherry’s whereabouts at a specific time and place (her constituency office) which prompted a police escort.

Cherry also made a barely-veiled attack on Sturgeon’s leadership, saying, “The problem we have is that from the moment the first parliamentarian complained against was hung out to dry [a reference to colleague Michelle Thomson?] a signal was given to those with petty motivations that if you seek to smear an SNP parliamentarian the party won’t get behind them, even if they are exonerated.”

She also claimed to be surprised “when no one from the leadership contacted me to inquire after my wellbeing.”

There is a simmering row, too, within the SNP over transgender rights. Sturgeon is one of those who believe people should be able to self-declare their sexuality. However Cherry, as part of a 15-strong group, signed a letter urging the Government not to rush into “changing the definition of male and female”. By appearing to pick a side she was also involved in another Twitter storm when she was accused of “misgendering”, calling someone a 'him' when they clearly wanted to be a 'her'. The dispute over the reforms to the Gender Recognition Act continues.

She also queried the main conclusions of Andrew Wilson’s Growth Commission report, on the currency issue, criticising its “softly, softly” approach, and she also wants an indyref2 sooner rather than later. She has said that another referendum isn’t a sine qua non and that, presumably, Sturgeon, with a parliamentary majority, could simply declare independence.

READ MORE: SNP’s Joanna Cherry denies bullying claims

So on three of the main planks of Sturgeon and the SNP leadership she is at odds. On the timetable and manner of holding an independence referendum, on the currency proposals and on transgender rights.

She is also a supporter of Alex Salmond, “liking” a series of tweets backing online calls to the former First Minister to replace the present one. She has also endorsed tweets calling for the Scottish Government’s Permanent Secretary Leslie Evans to resign. Evans was the central figure in the botched inquiry into sexual harassment inquiries against Salmond.

It all adds up to continuing strife within the SNP and Cherry is clearly not about to back down.