The public is undoubtedly in favour of politicians who deliver on manifesto pledges.

And that is what Scottish ministers are trying to do in consulting on a future Gaelic Medium Education (GME) Bill.

At the centre of this is a manifesto promise by the SNP to "examine how we can introduce an entitlement to Gaelic medium education".

The principle is sound enough. A clear, transparent and consistent process should be put in place whereby authorities can address parental requests for their children to be taught in Gaelic.

But should this be an enforceable right for parents? Glasgow's Education Director Maureen McKenna has responded to the Government saying such a law would be foolhardy. It risks creating a demand that cannot be met, she argues, partly under current council budgets, but in particular in terms of suitably skilled teachers.

Councils such as Glasgow - which is committed to GME - must be able to work at a realistic pace, or risk employing sub-standard teachers. The shortage of qualified GME teachers is such that Glasgow might end up recruiting teachers because of their ability to speak Gaelic rather than the quality of their teaching.

Mrs McKenna's points are reasonable. Any legislation must be workable. Gaelic medium education is popular and demand is growing. It is arguable that by insisting on a legal entitlement for families to GME that this would push councils to deliver, and chivvy those that might otherwise drag their heels.

But sufficient resources must genuinely be available if this approach is taken, and the Government would surely need to invest more to help education authorities deliver.

A key issue, as Mrs McKenna points out, is the extent to which Gaelic is a visible, vital element of public life. Until it is, she claims, GME cannot flourish, no matter how many people learn to be fluent in it. Hence, paradoxically, Gaelic learning is both necessary for and dependent on the language's health in wider society.

But in the context of tight budgets and hard decisions, it would further diminish the ability of councils to make decisions on the basis of local priorities if they were forced to make cuts in other areas to meet a national SNP commitment on GME.

The practicalities are also relevant. Glasgow is right to point to the Welsh experience, where it took 20 years for just one of its secondary schools to be in a position to deliver 100 per cent of its education through the medium of Welsh.

If Wales, where 25 per cent of the population speaks the language, struggled to find sufficient teachers with the necessary language and educational skills, it is bound to be more challenging in Scotland where just two per cent of the population has some Gaelic competence.

We would not do anything in our education system that appeared to be setting pupils up to fail. Neither can we set up local authorities to fail, by insisting parents have a legal right to GME when the fact is that Gelic conditions make that demand impossible to meet.