By Caroline Wyatt BBC correspondent in Paris

For the first time, British troops marched at the head of France's Bastille Day parade - the annual celebration of the French revolution - to mark 100 years of the Entente Cordiale.

Under a blue sky and a blazing July sun, a band from the Royal Marines struck up Land of Hope and Glory as British troops stepped out onto the Champs Elysees.

There were nearly 200 British personnel at the parade

It wasn't the tune most French expect to hear on Bastille Day, but on the VIP podium President Jacques Chirac didn't bat an eyelid as he was serenaded with a medley of British military marches.

Nor did he blink as France's most important parade was led by the Grenadier Guards, followed by the Household Cavalry - and at the front, Captain James de St Jean Pryce on a horse named Agincourt, the battle in which the English under Henry V roundly defeated the French during the 100 Years War.

"Poor Agincourt - she's been the butt of rather a lot of controversy, all of it entirely innocent," Captain Pryce says.

"The horses are all named using a letter of the alphabet for the year they're born in - and Agincourt just happened to be the name of the battle we chose."

More tactfully, two other cavalry horses, Waterloo and Trafalgar, stayed firmly in their stables at home.

But as row upon row of cavalry, infantry and armoury made their way down the imposing avenue, the British presence was all about showing that those battles with France are a thing of the past - and that thanks to the Entente Cordiale, old foes became firm friends.

Splendour

No mention of more recent disagreements on Iraq, or the future of Europe.

For the top brass watching the parade, such as General Sir Mike Jackson, chief of the general staff of the British Army, it was a display that showed both nations marching firmly in step.

"It's been a wonderful day," he said with a smile.

It's a great day for the friendship between English and French Parisian businessman UK troops join Bastille Day march In pictures: Bastille Day parade

"The weather's great and it was very special to have British troops taking part in this great parade of the 14th July to mark 100 years of our two countries being allies, in the foreign policy and defence sense as well."

And the splendour of the British contingent - swords, helmets and medals glinting in the sun - certainly went down well with the Parisians who lined the Champs Elysees.

They cheered as the Grenadier Guards, the Kings Troop of the Royal Horse Artillery and the Household Cavalry led the parade and the Red Arrows flew overhead at the end.

One young woman was overwhelmed by the glamour of the British cavalry regiments.

"Beautiful! Very magnifique," she enthused.

Pride

Others saw a rather more lasting message from the festivities.

"I am very happy to see the French and British army together on the Champs Elysee," one middle-aged Parisian businessman told me.

"It's a great day for the friendship between English and French. I am thinking about the future of Europe, and it can only be built on a great friendship."

The British cavalry impressed the Parisians

And for some British onlookers, the parade was quite simply a moment for quiet pride.

One man, visiting Paris, seemed overwhelmed by the display. "It was great to see the British troops - I had tears in my eyes when I saw the Grenadier Guards and the Household Cavalry.

"I think it was a real symbol of the friendship that there should be between our two countries."

After the parade, though, it was a different treaty - this time the European Constitution - which unexpectedly took centre stage in President Jacques Chirac's Bastille Day address.

In a surprise move, he told the nation France would hold a referendum on the constitution.

A decision which directly affected the French people, Mr Chirac said, must be voted on by the French people.

Risky move

Initially reluctant to offer such a vote, the French President was pressured into it both by his own political party, and by the British prime minister Tony Blair's decision in April to hold a referendum in Britain next year.

For now, opinion polls show at least two thirds of the French would say yes to the European constitution.

But by the time the referendum is held, in the second half of next year, the situation could look different.

Many in France are worried about being part of a larger Europe, in which Paris may well wield less influence, while others could use a referendum as a protest vote against an unpopular French government.

Despite the Entente Cordiale celebrations, Mr Chirac may be feeling rather less than grateful towards Mr Blair for adding to the pressure for this risky political move.