Greta Thunberg is inspirational but she has also brought a disturbing notion along with her

Let me place two cards on the table at the start. One. I find Greta Thunberg, the 16-year old prophetess of climate Armageddon, a presence at once impressive and alarming. But I find the fawning adulation with which she was received by political London plain disturbing.

Was it really necessary for a whole coterie of MPs, including the environment secretary, Michael Gove, to sit so seemingly entranced by her words?

Or for the prime minister to be criticised for not dropping everything to sit at Queen Greta’s court? Sorry, I think not.

It is understandable that politicians might welcome any unifying distraction from Brexit, but might their attendance have been driven less by concern about a warmer world than by their desire to look less stale and male and more “down with the kids”, especially with local and maybe EU elections and possibly a leadership contest pending?

Two. My enthusiasm for Thunberg and her cause may have been somewhat coloured by finding my route home last Sunday evening blocked at Hyde Park Corner, and having to watch as the police – in what seemed to me an unnecessarily friendly and ingratiating manner – escorted a rag-tag group of costumed protesters who could easily have been confined to a single lane.

Now, I admit, I wanted to get home; I had spent hours travelling already (oh dear, yes, some of them in a plane), and it may be unfair to lump together a police decision to close off a whole traffic system for far longer than seemed necessary with Extinction Rebellion or its heroine.

So, yes, you may object at the outset that I come to this whole complex of questions with somewhat jaundiced eyes. What is more, Thunberg has left now – she kindly posted a selfie from her berth on an eco-friendly Swedish sleeper train to tell us – and our politicians are getting back to Brexit.

She is not, though, forgotten. And out of the ubiquitous, and largely friendly, media coverage of her stay here has re-emerged another question. If 16-year-olds can be as informed, as articulate, and as politically impassioned as Thunberg, why on earth do they have to wait another two years to cast a vote in UK elections?

Is it not high time to recognise that 16 is the new 18, and follow Scotland’s example in reducing the voting age for its 2014 referendum?

In fact, Scotland’s decision to extend the franchise was a one-off, the reason given being that this particular vote would determine Scotland’s future, so more young people should have a say. The same argument was advanced – without success – for including all UK 16-year-olds in the 2016 EU referendum, and it is now used in retrospect to claim that the oldies’ Leave vote “stole” our children’s future. So far, though, the campaign to reduce the UK voting age has not become a clamour. And, personally, I hope it does not.

First, because those who argue most forcefully for lowering the voting age commonly have an agenda that goes beyond the supposed new maturity of 16 year olds.

It was supporters of Scottish independence who chiefly advocated extending the franchise for the 2014 referendum, with polls suggesting young people were disproportionately on their side.

Something similar applies to the UK’s EU referendum. The belief – borne out in estimates that 73 per cent of voters aged 18-24 chose Remain – was that a younger electorate would make a Remain majority more likely.

In the past, more generally, it is the political left that has tended to favour a lower voting age, in the expectation that more young people would vote left than right.

The effects of lowering the age, however, are mixed. Austria reduced the voting age to 16 in 2007 (on the initiative, incidentally, of the Greens) and remains the only EU country to have done so. Not even Thunberg’s progressive Sweden has taken the plunge. It has been argued, what is more, that the immediate effect on Austrian elections was a boost not for the left, but for the far right, as the change preceded the ascendancy of Jörg Haider.

Nor is it clear how far lowering the voting age encourages young people to vote. In the Scottish referendum, the turnout of under-18s was lower than for other groups (75 v 85 per cent), as it was in the UK’s EU referendum – though perhaps not as dramatically low as some estimates suggested. And while younger voters tended to vote Remain in that referendum, a higher turnout of young people would not have changed the result.

In short, giving 16 year olds the vote because politicians want a particular result seems to me quite wrong, and may have rebounded in Austria.

Lowering the age in the hope of galvanising young people and giving them a bigger stake in their country’s future runs up against the fact that fewer young people tend to use their vote.

The best way to remedy that, it seems to me, is for politicians to do a better job of getting their message across to young voters – Jeremy Corbyn in the 2017 UK election offers an example – and to make registration and voting simpler. I am all in favour of secure e-voting.

The most compelling argument against lowering the voting age for me, however, has little to do with either participation rates or even politics.

I was one of the early beneficiaries of the reduction in the UK’s voting age from 21 to 18, which took effect in 1970. While one of the considerations was indeed to give younger people a bigger stake in the political process and recognise the greater maturity, as it was seen, of 18 year olds, another was to end some of the glaring contradictions that had evolved in terms of citizens’ rights and responsibilities.

There are still contradictions, but they are fewer. You can drive a car on a full licence at 17, but you must stay in full-time education until 18. You cannot marry or enter a civil partnership (without parental permission) until you are 18, or fight on the front line (in most countries you cannot even join the military before then), or drink alcohol in public. You cannot take out a mortgage; nor, if you are charged with a criminal offence, can you be named.

If the voting age were reduced, would all those restrictions – which are rather protections – be lifted? And if they weren’t, what happens then? Either there would be a host of new inconsistencies as to what someone can do aged 16 or 18, or the right to vote would cease to be a recognition of full adulthood; it would merely be the right to vote.

Surely, though, voting should be the preserve of adults. Thunberg has many assets, but it is her utter confidence that at once seduces and repels. It defines her, but it also betrays her youth. She does not qualify to vote in Sweden. Nor should she become the poster child for giving 16 year olds the vote here.