Credibility is such an important thing for CEO’s of companies and for politicians. For the latter in particular it is a scarce and fragile commodity. Remember Theresa May, that savvy operator and safe pair of hands who became leader of the Conservative Party and hence Prime Minister? - gone, though still just in office. Boris Johnson, the heartthrob of every southern English Conservative constituency association - I sense a plug has just been pulled somewhere and his political capital might be draining away - though he has an ability to recover from scrapes which would finish others.

For some leaders, Theresa May being one, the issue is not honesty - she seems entirely honest - it is of competence and judgement. Curiously Jeremy Corbyn still has credibility - we may disagree profoundly with what he says and believe he would be a disaster as prime minister - but he is essentially honest and people warm to that. Nigel Farage comes across as an even better example of the same thing - he speaks in a way all can understand and says what many others think - at the moment a significant proportion of the electorate love him for it - becoming Prime Minster is no longer an unthinkable outcome for Nigel.

In both business or politics, credibility can erode slowly or be crippled with a single blow. How long will Boeing take to recover from its action and inaction regarding the 737 Max? - trust in the integrity of the company has suffered real damage. Can British banks regain the trust of their customers - they have a long hard road ahead before they achieve that. Philip Green - what can one say?

In Scotland the SNP administration and Nicola Sturgeon in particular started with credibility bestowed not by proven competence but by newness. We tend to give people the benefit of the doubt and the SNP administration and its current leader had that.

What is now sapping the SNP Government’s political strength is growing questions about both competence and honesty.

Have our roads, railways, hospitals and schools improved on the SNP’s watch - they have not, yet they lie squarely within the Scottish Government’s powers and budget. Why should we trust Nicola and her crew with yet more power when they have failed to use effectively what they already have? Drip, drip, drip, our perception of their competence fades away. The brightness of the new does not last forever.

Perceived honesty is an even more important commodity than competence. Do we all really believe the SNP’s narrative that Scotland has been insulted and ignored in the Brexit debate rather than the more mundane truth which is just that we are one of the parts of the UK which wanted a different result? Do you really believe that the promised reduction in Air Passenger Duty was cancelled because of a sudden realisation by Nicola Sturgeon that we had a climate emergency or do you believe that was a politically expedient way to disguise a failure to deliver and create a green crowd pleaser? Obesity and falling basic education standards are at least as great emergencies as climate change but how inconvenient to have to admit that if you have actual direct responsibility for tackling it.

If you want to find positive and sustained credibility in business look no further than John Lewis and M&S. We know what they do, they do it well, they behave fairly and consistently towards their stakeholders. Politicians generally - and Scotland’s in particular, should take a leaf out of their book; talk less, divide and spin less, deliver more.

Pinstripe is a senior member of Scotland's financial services community.