Michael Matheson is an albatross around Humza Yousaf's neck - Brian Monteith

It may be a cliché but it is no less true; it is not the original sin that tends to take people down but the subsequent cover-up of the sin that becomes a far more damaging story.

So it is with Michael Matheson’s near-£11,000 expense claim for using a parliamentary iPad on holiday; what should have been an easy enough problem to deal with, grew and grew because the original sin was not quickly admitted but repeatedly ignored and covered up.

Now the saga should not only bring down the SNP Cabinet Health Secretary, worse still for the Scottish Government, it threatens the First Minister’s reputation, possibly beyond repair.

It is beyond my comprehension how, on being presented a bill just short of £10,935.74 for use of a parliamentary iPad during the Christmas recess – primarily over a few days when in Morocco – Matheson nor the parliamentary authorities did not do the due diligence to find out exactly what data usage was responsible for such a bill.

Did Michael Matheson really believe he had done so much constituency work on his Moroccan holiday that it would have run up such a bill? Did he not ask himself why on this occasion it was so big – or should we expect to believe he has had other large bills such as that in the past?

Is this really the standard of competence and regard for public finances that we can expect from Scottish Government Ministers, never mind ordinary MSPs?

Having believed it was the job of the public purse to pick up the tab why, when discovering on Thursday 9th November it was younger members of his family watching football via the use of the iPad, did he wait until Tuesday to break the news to the First Minister? Why not contact Humza Yousaf immediately, offering to resign and thus prevent further denials being made by himself, the First Minister and official spokespeople doing their job?

Why do SNP ministers so often feel the need to continue with a lie by telling further lies?

On Monday 13 Mathieson was asked by The Scotsman about the iPad expenses and again he repeated there was no personal use. It was a moment requiring the utmost candour. Matheson could have confessed then to an unwitting mistake – without later mentioning his sons, offering to step back from his post, find solace in recognising his error and then seek to rebuild his reputation and be available to help his party when called to do so again.

Instead he waited until Wednesday 15, leaving the First Minister to continue denying there was an issue of trust – and a question over the appropriateness of his Ministers’ expense claims. Even after learning of Matheson’s new version of events the First Minister continued to defend his behaviour as appropriate. Now Humza Yousaf says the issue is closed – but Matheson’s conduct hangs around the First Minister’s neck like an albatross.

It is not as if SNP Ministers are new to the problem of lying in an attempt to either win arguments or deny when great errors have been made.

It is a fact a Scottish Parliament Committee found that the previous First Minister, Nicola Sturgeon, misled parliament in regard to her handling of the Alex Salmond inquiry.

It is a fact that Angus Robertson was advised by officials that SNP government claims Scotland had 25 per cent of Europe’s offshore wind capacity was incorrect (being only 9 per cent) – yet he chose to repeat the lie.

It is a fact that when asked about what currency an independent Scotland would have First Minister Humza Yousaf says “the Pound” – but only last week Angus Robertson’s paper explaining how an independent Scotland would join the EU refuted this by stating Scotland would move quickly to have its own currency. Only one of those propositions can be true.

The problem of trust haunts the SNP at every turn. Be it statements about dualling the A9, completing two ferries on time and within budget, the opaque deal with Sanjeev Gupta for the Lochaber aluminium smelter – even to the date of the next independence referendum – there is rarely a time when an SNP claim now stands up to scrutiny.

All of that is before Police Scotland establishes the evidence on what has exactly happened to the donations made to the SNP intended for an independence referendum that has never taken place.

It is not just ordinary members of the public who cannot know if they are being told the truth by SNP ministers – for how can fellow Cabinet ministers sitting round the table look Michael Matheson straight in the eye and know whatever he is telling them about the state of the NHS is not covering up a big lie?

And if they, having been misled already by Matheson, in their heart of hearts have doubts about the veracity of what he says – why should we not feel the same?

Humza Yousaf can still solve this problem by showing leadership; dismissing Michael Matheson for incompetence and a shocking lack of candour – then committing to a parliamentary inquiry chaired by a member of an opposition party.

If the First Minister fails to take the initiative and hold his Health Secretary to account then Matheson shall remain that albatross around his neck – reminding everyone, the media, MSPs of all stripes, and the electorate – that SNP politicians, be they speaking in a party or Government capacity cannot be trusted. Their words cannot and should not be taken as honest but must be doubted whenever their lips move or their fingers punch the keyboard.

The First Minister has only has hours, maybe a day to act – after which it will be too late and the stench of distrust will follow Matheson, Yousaf and the SNP Government wherever they go.