France and the UK have signed a treaty to speed up the processing of migrants in Calais, French President Emmanuel Macron announced on his first UK visit.
After talks with UK PM Theresa May at Sandhurst military academy, he said the treaty would offer a "more humane approach" and be "more efficient".
But he suggested France would not bow to UK demands to include financial services in any post-Brexit trade deal.
Mrs May praised the "uniquely close relationship" between the two nations.
She said both leaders remained committed to the "Le Touquet" border agreement in Calais - the UK has announced an extra £44.5m to be spent on beefing up Channel border security.
Mr Macron said the Sandhurst Treaty signed on Thursday - the first joint treaty on the Calais border in 15 years - would "enable us to improve the relationship and the management of the joint border" and reduce the time taken to process migrants.
It would mean the time taken to process migrants hoping to come to the UK from Calais, would be reduced from six months to one month for adults and 25 days for children.
It "will enable us both to have a more humane approach to these people and to be more efficient" while also encouraging trade through the Channel ports, said the president.
Mrs May said it was in Britain's national interest, as well as France's, to commit more resources to Calais security and stressed the two countries' joint commitments to defence and security measures.
She said a combined joint expeditionary force would be ready to deploy up to 10,000 troops "quickly and effectively to face any threat" by 2020.
And the prime minister said a multi-million pound deal to build 36 A380 passenger aircraft for Emirates Airlines had been signed by Airbus, which has plants in France and the UK.
She also confirmed that the Bayeux Tapestry will come to the UK in 2022 - a gesture President Macron said he hoped would "open a new chapter when it comes to our cultural co-operation and scientific co-operation".
"We are making a new tapestry together," he said.
The summit between Mrs May and Mr Macron, at the Royal Military Academy Sandhurst in Berkshire, also featured the first meeting of the heads of Britain and France's five intelligence agencies, and is being attended by British cabinet ministers and their French counterparts.
And with Brexit very much on the agenda for both nations, Mr Macron said that the history between the two countries could not be "impacted by changes in institutions".
'Be my guest'
Challenged about his opposition to including financial services in any EU-UK free trade agreement, he said: "I am here neither to punish nor to reward. I want to make sure that the single market is preserved because that is very much the heart of the EU."
He said if the UK wanted access to the single market, including financial services, "be my guest. But it means that you need to contribute to the budget and acknowledge European jurisdiction".
New Channel 'link'?
Mrs May said she recognised that there would be "a different relationship in future" but added: "I think the City of London will continue to be a major global financial centre. That is an advantage not just for the UK, it's actually good for Europe and good for the global financial system."
Meanwhile Foreign Secretary Boris Johnson has hinted at the prospect of a second crossing for the English Channel - tweeting: "Our economic success depends on good infrastructure and good connections. Should the Channel Tunnel be just a first step?"
A source close to the foreign secretary told the BBC that Mr Johnson had suggested to President Macron that a new "fixed link" between UK and France was needed.
Other commitments include the deployment of three RAF Chinook helicopters in Mali, where French forces are fighting Islamist militants, and France sending more troops to reinforce a British contingent in Estonia on Nato's border with Russia.
Downing Street said the RAF Chinooks would offer a "niche capability", providing logistical support for the French operation in Mali, but that Britain would not be committing combat troops.
The border offer
During last year's French election campaign, Mr Macron said he wanted to renegotiate or scrap the 2003 Le Touquet agreement, which established French border controls in Britain and UK controls in Calais.
The agreement means undocumented migrants barred from entering the UK stay in France - many in makeshift camps. Up to 700 migrants are in the area, despite the camp known as the "Jungle" having been dismantled in 2016.
The UK government is already thought to have spent more than £100m on security in the area over the past three years, and officials said the number of illegal attempts to enter the UK fell from 80,000 in 2015 to just over 30,000 last year.
Other "juxtaposed" border controls are in operation at Eurostar stations in France and Belgium.
How the leaders shape up
By James Robbins, BBC diplomatic correspondent
Britain and France carry much the same weight in global affairs. Both sit at the world's most exclusive tables of power - the Security Council and the G7 - and the sizes of their populations and economies are broadly similar too.
But while President Macron commands France, including his parliament, after last year's stunning electoral successes - the same cannot be said of Theresa May.
Sharp disagreements over the UK border with France are difficult to resolve. Mrs May has conceded extra money for border security in Calais - and has separately offered Chinook helicopters to move French troops more safely over Mali.
Mr Macron, meanwhile, has offered the loan of the Bayeux tapestry. But Brexit still threatens to overshadow all this bonhomie. When it comes to Europe, these two countries are pulling in radically different directions.