WHEN Nicola Sturgeon set out to close the attainment gap between pupils from rich and poor homes, her tone was urgent, ambitious and elevated.

She declared: “My aim - to put it bluntly - is to close the attainment gap completely. Its existence is more than just an economic and social challenge for us all. It is a moral challenge. Indeed, I would argue that it goes to the very heart of who we are and how we see ourselves as a nation.”

The First Minister has made it a defining test of her leadership.

But children who were just entering the school system when the First Minister gave that speech in August 2015 are now in P3.

Progress, as the Scottish Liberal Democrats put it, has been glacial, with the latest example ministers consulting on measuring the gap.

Not a progress report on success so far, nor a blueprint for fixing the problem, but simply a scheme to quantify the gap in the first place - and even this will not be finalised until at least December, when those P3 pupils will be almost half-way through their primary years.

It is an unconscionably slow response to a “moral challenge”.

That said, the proposals do appear well-founded.

Ministers propose a basket of eight headline measures and 17 more detailed “sub-measures”, starting in infancy, with an assessment of social, emotional and behavioural development.

The key measures cover literacy and numeracy in primary and secondary schools, and exam results up to advanced higher.

Finally, there is a measure of participation by the 16 to 19 age group in school, work or study.

The sub-measures include mental wellbeing and exclusion rates in primary and secondary.

The baseline figures, based on 2016/17, are due in December.

However 2015/16 data starkly illustrate the scale of the challenge.

The number of children from the most deprived areas of Scotland achieving satisfactory results in literacy and numeracy in both primary and secondary is consistently 16 to 20 percentage points lower than that of children from the least deprived areas.

The gap is wider in the exam results so crucial to future careers and study, with just 43 per cent of children in the most deprived areas leaving school with one or more Highers compared to 81 per cent in the most affluent areas.

The problem is worst of all in secondary exclusions, which ran at 15.2 per 1000 pupils in the most affluent areas, but 95.2 in the most deprived, an 80-point gulf.

There is clearly much to be done, and the consultation also sheds a welcome light on what the SNP meant by its pledge to “substantially eliminate” the gap over a decade, with “stretch aims”, or loose targets, up to 2024/25.

But what is missing is a plan to measure systematically how SNP efforts to close the gap - extra funds for headteachers, for instance - are working.

If these are to be taken seriously, rather than seen as manifesto gimmicks, they too must be rigorously assessed, with the best pursued more keenly and the junk discarded. That way the gap can be closed sooner still.