Britain is a nation made up of moderate monarchists and reluctant republicans, according to a Guardian/ICM poll. More people are looking forward to an extra day off work than watching the royal wedding – but support for the monarchy has nonetheless climbed notably since the crisis following Princess Diana's death. The country is in no mood for a revolution.

The poll shows a large majority think the monarchy is still relevant to national life, makes Britain more respected around the world and is better than any alternative. But there seems to be tolerant scepticism rather than royalist hysteria around the wedding itself.

Only 37% agree that they are genuinely interested in the wedding, while 46% say they are not. Women are much more likely to be interested than men, and only 18% of all people questioned say they are strongly interested in the event.

Even so, 47% agree they will probably watch it on television this Friday, including a majority of women and people aged 18-24. Almost the same proportion, 49%, say they are more excited by the idea of an extra bank holiday than the wedding – only 31% disagree.

The poll includes some questions proposed by Guardian readers online, among them the suggestion that the wedding will boost the nation's feelgood factor at a time of economic uncertainty. Almost everyone, monarchist or not, agrees that the wedding will cheer Britain up: 75% say yes, only 17% no. That may be one reason why the poll seems to dash republican hopes that the monarchy is becoming an outmoded institution. Instead support for the crown, if anything, is growing.

More people think the monarchy is a unifying national institution than one that divides the country and reinforces the class system. Almost half those questioned, 47%, say it is a unifying force, against 36% who think it a divisive one. Only among Labour supporters do more people think it divisive than unifying.

And despite all the celebrity hype surrounding the wedding, only 32% think the event is more about glamour and celebrity than British values (52%).

More people think the crown should pass directly to Prince William rather than Prince Charles, 46% to 40%. But most people also think there is nothing wrong with having to call a member of the royal family "your highness": 64% approve of the practice and only 29% do not.

So the age of deference is not quite dead. There's also a strong shared national belief that the monarchy is something that improves Britain's image around the world. While 60% say it does, only 2% think it definitely does the opposite, with 36% saying it makes little difference either way.

More significant, perhaps, are changing attitudes to the monarchy's place in British life. A strong majority among people of all political persuasions and social groups think that Britain would be worse off without the monarchy. While just 26% think the country would be better off getting rid of the royal family, 63% say the opposite.

There has been a small regrowth in royalist support since the nadir following Princess Diana's death. In August 1997 a Guardian/ICM poll found that only 48% thought the country would be worse off without the crown, 15 points lower than now. By August 1998, that had risen to 62%, one point lower than now. Despite massive political and economic shifts in the decade since then, attitudes to the monarchy seem almost static.

There is hope, though, for republicans in the fact that the most enthusiastic supporters of the monarchy are pensioners, and young people are less keen. Among 19-24s, 37% think Britain would be better off without the monarchy, 10 points higher than the average.

Even so, 67% of all people – including 73% of women and 57% of 18-24s – think the monarchy is relevant to life in Britain today. Only 32% disagree. Again, there has been almost no shift in opinion over the last 10 years. In May 2002 a Guardian/ICM poll found that 66% saw the monarchy as relevant and 33% thought not – figures almost identical to the ones in this month's poll.

As for the future, the Queen's death could make a big difference to attitudes. Almost everyone, 89%, thinks Britain will still have a monarch in 10 year's time – but that belief drops sharply when people are asked about the next 50 and 100 years.

A narrow majority, 57%, think there will be a place for a British monarch in 50 years but only 40% think William and Kate's descendants will still be on the throne in 2111.

Even so, confidence in the future of the monarchy has grown since 1997: then only 38% thought there would be a monarch in 50 years time and just 26% thought the crown would survive the next century, 14 points lower than today.

There's also a widespread feeling that a monarch such as the Queen should retire rather than cling on if they cease to be mentally or physically capable. While 64% think the monarch should retire, only 31% do not.

ICM Research interviewed a random sample of 1,003 adults across the United Kingdom aged 18 and over by telephone on 15-17 April 2011. Interviews were conducted across the country and the results have been weighted to the profile of all adults.