Britons are expected to spend more than £800m celebrating the Queen's Jubilee, according to new research.
The figures is almost twice as much as the country spent during last year's Royal wedding festivities, said moneysupermarket.com.
The online price comparison site survey estimates that people celebrating next week's event plan to spend an average of £40 on Jubilee-related items.
"Our research has shown the British public is gripped by Jubilee fever with almost half of us keen to mark the 60th anniversary of the country's longest reigning monarch," said Clare Francis from the website.
"With an extra day off work for most, it makes sense that people want to mark the occasion with a celebration of their own and that many plan to buy a keepsake."
The findings are in stark contrast to warnings from senior economists that the extra bank holiday will have a negative effect on the British economy.
"The greatest areas of disruption may be in areas like manufacturing because you might have at that time more extended shutdowns at plants," said Ross Walker, chief economist for Royal Bank of Scotland.
"You may get disruptions to the supply chain which could hit production industries more than other sectors so manufacturing seems particularly vulnerable but I think it will be quite broad-based."
But some manufacturers are rubbing their hands with glee as the Jubilee creates a surge in orders.
The Emma Bridgewater pottery at Stoke-on-Trent is set to double its predicted sales - with £1.5m worth of commemorative products.
Demand has far outstripped Royal wedding sales with major retailers increasing orders up to sevenfold.
The company expects to make more than 200,000 pieces of Diamond Jubilee ware.
One item - a crown-shaped dish with lid priced at £100 - was predicted to sell 300 and more than a thousand have already been sold.
Co-owner Matthew Rice said: "We have never seen demand such as this. When people are happy, they spend money. When people are sad they don't. It's as simple as that.
"These are happy, brilliant events and they will stimulate trade. It's good for the country - as is a day off."
He has harsh words to those who say the Jubilee is bad for business.
"I think 'bah humbug!' is the phrase for that. Get a grip! Shut the doors! Get out and have a good time. If you are so sold on your business that you can't enjoy a few days of bank holiday, then something has gone very wrong with your life," he said.
North Yorkshire flag making firm 'Flying Colours' agrees. Owner Andy Ormrod said the firm had received orders for Union flags from ex-pats in Australia, Europe, America and it started snowballing from there.
"Since January it has just been amazing. The orders are coming from British business, Councils, corporations, theme parks... You name it."
Analysts will have to wait until the economic figures are out for the second quarter for an accurate reflection of the Jubilee effect.