The future of social care, President Nicolas Sarkozy declared, "is a matter of such importance and gravity that ideology has no place". His opponents scoff, among them Martine Aubry, one of the frontrunners to be the Socialist party's candidate against him in the presidential elections due in 2012.

Viewed from the British side of the Channel, Sarkozy has made a striking promise to create a "new branch of the welfare state" to provide care for old people and those with disabilities. France has 1.1 million dependent old people, their numbers expected to grow by 1%-2% to the middle of the century, when the over‑85s could number 5 million.

Alarmist voices have sounded, but France has heard little of the partisan hysteria audible in Britain, where spending on care for old people has been proportionately higher than in France. Sarkozy promises to lay out a plan by this summer, in good time to give him a populist theme for the presidential campaign. (By then we ought to have sight of proposals to come from Andrew Dilnot, the Oxford economist commissioned by the Cameron government to rethink social care; they will make for a fascinating comparison.)

It's true that Sarkozy, after grandstanding on social care when he was elected in 2007, has vacillated. His latest line is that social care won't be a formal "fifth branch" of the French welfare state. Its four pillars are family benefits, health, coverage for accidents at work, and pensions. They offer relatively generous statutory entitlements, funded by insurance schemes paid for by statutory employer and employee contributions, topped up by general taxation. Instead, Sarkozy's extension of social care is to come from private insurance, some tax funding or even (this came from Laurent Hénart, the president of the national agency for personal services and a pro-Sarkozy MP) the proceeds of French workers giving up a day's leave each year. But the state will organise and underpin it.

How unlike Britain: in France, cross-party commitment to welfare runs deep, as does belief in the necessity and benignity of "l'état". Politicians on the right and the left use the word solidarité with sincerity (the National Front is statist, too, though its definitions exclude "immigrants" from the national compact). Perhaps solidarity is the modern expression of the 1789 cry for "fraternity". The Sarkozy government has a minister for solidarity and maintains the solidarity tax, only one of several payments by general taxpayers and employers levied in the name of strengthening social cohesion. On the annual journée de solidarité employees' pay is earmarked for old people's charities.

Fraternity begets equality. The French welfare state delivers a society where the gaps between rich and poor are smaller than in the UK. France is one of the few western countries where poverty and income inequality have fallen during the past 20 years. Meanwhile in the UK, income inequality is higher than it has been for 30 years. An impulse towards égalité is imprinted deep in the French political DNA: the Lavialle polling institute recently found that nine out of 10 French people think the income gap is still too large. The French are more convinced that the state is a force for good: leftist criticism of Sarkozy's government masks deep underlying agreement on the need for a big and benign state.

All this finds expression in willingness to spend on pensions, income support, health and social services which together amounts to 33% of national income, the highest in the Organisation for Economic Co-operation and Development, where the average is 24%. The UK falls below average, on 23.3% – but figures from this year will show a steep drop. The French benefits system is "Bismarckian", based on insurance funds. For health the employer pays 12.8% of earnings, the employee 0.75%; in state pension contributions 8.3% and 6.65% respectively, up to an earnings ceiling. But as in Germany, the funds still need large subventions from the state. Households pay a hypothecated tax, topping up the funds, which cover health, maternity pay, disability and pensions. Separate insurance covers family benefits, industrial accidents and unemployment insurance.

Since the revolution, the place of Catholicism in French life has been fiercely contested. But church and state have long agreed to encourage child-bearing and support mothers. Though the birth rate fell as elsewhere in Europe, it is higher than in the UK. In both countries the birth rate picked up from the boom years of 2002 onwards, yet both countries still have fewer babies than funerals. Ever since a great drive after the first world war to make up for its missing dead, the French state has been energetically pro-natalist, traditionally favouring families nombreuses. But there is not much sign of church influence in observance of marriage vows. In both France and the UK, figures for fertility and births outside marriage have broadly risen in step. Some 42% of UK births are out of wedlock; in France it's over 50%.

But better education and anti-poverty measures may explain the fact that there are far fewer teenage mothers in France, with 10 babies per 1,000 females aged 15-19 compared with the UK's 25. Average age for first motherhood is in the late 20s, with French mothers having their first baby 15 months younger than British women.

Maternity pay is more generous but paternity leave is the same in both countries. A larger proportion of French women of working age take jobs than in the UK. In pay terms they are better treated, too. In Germany men on median earnings get 23% more than women, in the UK 21% more, but in France, the pay gap is 12%. That one difference contributes significantly to their greater overall equality.

French families get more help. Public spending on early years is the highest in Europe after Iceland and Denmark, at about 1.1% of national income – the comparable British figure is 0.7% (since these 2005 EU figures, Labour expanded nurseries and childcare rapidly, but they are now contracting again fast). French benefits are, however, relatively less generous to lone parents, who are bringing up about 13% of all children, compared with 24% of children in the UK. Unlike Britain, where Labour policy boosted the income of working lone parents with tax credits, they get no special financial encouragement to work.

Whether it's due to lifestyle, social security or high health spending, the French are long-lived. A Frenchwoman can expect to live 84.4 years, three years longer than her British counterpart and the highest in the OECD after Japan. For Frenchmen, however, life expectancy is 77.3 years, the same as for UK men.

The age structure in France is similar to Britain's – both nations are growing older. Even if the increase in the proportion of the population above pension age is going to be relatively small over the next four decades, the cost of ageing is a familiarly fraught issue in French politics. That is partly because French pensions are generous. Pension payments account for one in every seven pounds of French national income, the same as in Germany – while in the penny-pinching UK it is half as much.

The Chirac and Sarkozy governments have tried to water down pension entitlements, especially among public sector workers, at the same time as they have increased the minimum state pension. But the swing from left to right has reversed policy directions and social priorities. Under François Mitterand, the plan was to get older people out of the labour market to make jobs for the young, so he lowered the retirement age from 65 to 60 in 1983. With the same intent, and to improve everyone's work-life balance, the Socialists cut the working week to 35 hours in 2000. But now, in France as in Britain, the aim is to keep older workers in jobs and push up the retirement age (now 61) – a move resisted by the Socialist opposition. Financial incentives are now in place to encourage people to continue working beyond pension age – but half the workforce "retire" before they are 55. Policy has shifted, too, to encourage private pension savings. Fewer French people with disabilities work than in the UK, roughly 46% here against 39% in France – but people with disabilities are better treated: fewer live in poverty across the Channel.

All in all, France is a generous society, and it fights hard on the streets against attempts to cut back on good collective provision for pensions, benefits and health. Contrary to myth, it is not the power of its unions – France has fewer union members than the UK – but the power of collective will. As a result, it is a better country than most in which to be old, or sick or unemployed, or disabled or a little child.