THE SNP exists to deliver one political objective, but the party leadership seems keen to talk about anything other than the constitution at their conference in Glasgow this week.

Nicola Sturgeon, still scarred by the memory of backing a second independence referendum only to be rebuffed by voters at general election, wants to say as little as possible on the timing of another vote.

Deputy First Minister John Swinney, in a pre-conference press release, tellingly focused on the so-called domestic achievements of the SNP Government. Independence was only mentioned in passing.

But such a shift raises difficult questions for Ms Sturgeon, who is edging towards her fourth anniversary as First Minister. If she quit tomorrow, what would her legacy be? In what way has she shifted the power balance inside Scotland?

Politicians can achieve much in four years. By 1949, Attlee’s Labour Government had created the NHS, legislated for a “cradle to grave” welfare state and nationalised the railways.

In Mrs Thatcher’s first term, the Tories clamped down on “closed shop” arrangements in trade unions and allowed council tenants to buy their own homes. Many of Tony Blair’s most successful policies were pushed through in his first four years.

A like-for-like comparison would be unfair on Ms Sturgeon. Attlee, Thatcher and Blair enjoyed huge majorities and had the full powers of the state to alter society fundamentally.

However, Ms Sturgeon did inherit a majority from Alex Salmond, but lost it at the last election. She has also more powers at her disposal, including on tax and social security, than any of her predecessors. Our fifth First Minister has the opportunity to effect transformational change.

It is difficult to paint Ms Sturgeon as a leader with a radical record. Minimum unit pricing of alcohol was a bold move, but technically the legislation passed when Alex Salmond was First Minister. Integration of health and social care was a massive change, but have the public noticed?

Other policies seem symbolic rather than substantive. Ms Sturgeon’s child poverty targets become measurable in 2030 and she wants Scotland to become “carbon neutral” twenty years later. It is easy to set targets which will fall on others to meet.

As for plans to create a National Investment Bank and a publicly-owned "not-for-profit" energy company, these initiatives fall squarely into the category of “yet to be delivered”.

Ms Sturgeon can expect to be judged on the three totemic issues she can influence: the health service; closing the educational attainment gap; and cutting poverty levels.

On the NHS, which she used to run, some health boards have been so badly managed that they over-spent their budgets and incurred £150m in bail out loans. The Government solution is to wipe out the debts. Even SNP loyalists believe the move sends a message that financial profligacy will eventually be subsidised.

Education - the First Minister’s top priority - is faring little better. Swinney had to shelve plans for a “governance” bill and support for P1 assessments has crumbled. Some of the £120m “pupil equity fund” money given to headteachers has been spent reversing budget cuts previously passed on by the Government.

For Ms Sturgeon’s critics, there is no golden thread running through the piecemeal, incremental changes implemented by her Government. They want a vision and a narrative, not a re-spray or a minor refurbishment.

Scottish Labour leader Richard Leonard asked Ms Sturgeon the best question last week, which was ironic given the appalling time he was enduring with his warring colleagues. He noted the child poverty target for 2030 but said: “What is her target for 2019?”

Ms Sturgeon avoided the question. In other words, a Government which believes itself to be on the centre-left does not appear to have a twelve-month target for taking poverty in the right direction.

She also got her figures wrong. She estimated that a £5 increase to child benefit - a policy within her gift and called for by the opposition - would lift 20,000 children out of poverty. In reality, 30,000 kids would be affected.

Imagine the Government had implemented this policy last year and promised to repeat it until the next Holyrood election. Poverty levels would fall and Scotland would buck the UK trend.

The First Minister would also have a reputation for being impatient for immediate progressive change, rather than risk being known as a cautious technocrat content with tweaking the status quo.