If I were living in Wales, next week I would vote Welsh nationalist, for Plaid Cymru. But I would do so for what its leader claims to support but doesn’t talk about enough: independence. Wales is where I have spent a fifth of each year for almost all of my life. Its natural beauty, the charm of (most of) its towns and the talents of its people should render it the richest place in the UK outside London.

So why is it one of the poorest? The figures hardly bear reciting. Wales’s growth rate has limped at barely half of England’s for a quarter-century. Its GDP per head is lower than any region in the UK other than the north-east of England. Wales comes bottom of almost every UK league table on healthcare. The median waiting time for elective treatment has almost doubled since before Covid – much higher than the current level in England. And waiting times in major A&E departments in Wales have worsened over the past two years, with almost half of patients waiting more than four hours for treatment.

More than a third of Welsh schoolchildren are persistently absent, according to an Institute for Fiscal Studies report, a figure that has more than doubled since 2019. In its programme for international student assessment (PISA) rankings – the global benchmark for education quality – Wales was below the OECD average and falling ever further behind the rest of the UK. The proportion of 18-year-olds progressing to higher education was only 29% in 2025, compared with 37% in England.

This is not a matter of money. Wales spends more per head on health, education and social care than England. The reality is that Wales is badly governed. Since devolution in 1999, the Labour party has been in power in Cardiff, with £21bn of its current budget covered in a subvention from the government in London. The national anthem of Welsh politics has always been that this is not enough. Yet Welsh Labour splurges money. For some reason, it is increasing its Senedd from 60 members to 96 after May’s election. The government building in Aberystwyth, which was only built in 2009, may close due to low attendance, with only 15% of its staff turning up in March last year. Spending is reckless – witness the £46m recently blown on a quite unnecessary new River Dyfi crossing.

The idea of Celtic independence from Britain has long seemed absurd – at least to many people in England – but after next week’s elections, Scotland, Wales and Northern Ireland may be represented by parties with separatist ambitions. Such is the obsessive centralism of successive Westminster governments that the UK could yet share with the former Yugoslavia and Czechoslovakia a failure to sustain a stable union.

In the case of Plaid Cymru’s new leader, Rhun ap Iorwerth, Welsh independence is no more than an aspiration, perhaps worthy of a commission of inquiry. This aspiration would carry more conviction were he not promising yet more spending with no suggestion as to its donor. As with all separatists, he seems to think independence would be painless.

Yet there is no reason why Wales should be different from other smaller European nations such as Slovenia or Luxembourg. It is bigger than them, and rejoining the EU would make borders with England permeable. As for dependency, the case of Ireland glares at us from across the Irish Sea.

Ireland, on its departure from the UK in 1921, was desperately poor, defensive of its identity and hostile to newcomers. It behaved much as Wales does today, with its hiked taxes on holiday homes, and a proposed new tax on overnight tourist stays. Ireland duly got poorer. Then, in the 1960s and with a population smaller than today’s Wales, it took a deep breath and about-turned.

Dublin aggressively welcomed international firms with tax breaks and tourists with second homes. It backed its universities to keep talent at home. Helped by joining the EU, Ireland plotted a route to what became the Celtic tiger in the 1990s. This saw it roaring ahead of Britain in per capita wealth. Like Denmark, Ireland showed that in economics small can mean rich. Today, Ireland’s GDP per capita is significantly higher than the rest of the UK.

There is no reason why Wales should not do likewise. It has a fine labour force, albeit underemployed. It is a fine place to live. Its mountains are lovelier than the Cotswolds – if it does not wreck them with wind turbines. Its port of Milford Haven beats any in Ireland and its small towns are exquisite. It has some of Britain’s best cheeses, its best local paper, the Cambrian News, and its lowest house prices. Wales should be to the Midlands, Merseyside and Manchester what the south-east of England is to London.

So how to get from here to there? There are, of course, degrees of independence. I can see the objections surging over the horizon. But elsewhere in Europe people have found answers to centralist fanatics such as those in London. They start in self-confidence and end in self-reliance. Wales should set aside its identity paranoia, open itself up and slim itself down. If, as seems likely, ap Iorwerth wins next week, he should look across the water to Dublin’s example. There lies the future for Wales.

• Simon Jenkins is a Guardian columnist