Prime Minister Theresa May and her French counterpart Emmanuel Macron agreed a new border security deal on Thursday, through which the UK will pay more to France to stop migrants trying to reach British shores.
May also confirmed the loan of the Bayeux Tapestry from France, a historic work depicting the Norman conquest of England which she said would come to Britain in 2022 for the first time in over 900 years.
The two leaders, meeting for wide-ranging talks at the Sandhurst military academy near London, agreed that the UK will pay an extra £44.5 million (50 million euros, $62 million) for fencing, CCTV and detection technology in Calais and other Channel ports.
"The further investment we have agreed today will make the UK's borders even more secure," May said during a joint press conference with Macron.
While the two countries cooperate closely in numerous areas, including intelligence and defence, differences over migration have often strained ties.
The money is on top of more than £100 million already paid by Britain, following a request by Macron to contribute more cash.
At a press conference, May said she was "honoured" by the loan of the Bayeux Tapestry and the French president added he hoped it would open "a new chapter" for cultural and scientific co-operation.
"We are somehow making a new tapestry together," Macron said, rejecting any suggestion that it was intended to remind Britain of a victorious France.
The loan has been met with opposition by French experts who have warned about the delicate state of the 70-metre (230-foot) long embroidery.
The tapestry, which shows the English King Harold being killed by an arrow in the eye at the Battle of Hastings in 1066, is believed to have been created within years of the battle
- 'Entente chaleureuse' -
The leaders capped the summit at an evening reception at London's Victoria and Albert Museum, where they spoke of celebrating the two countries' shared history and values.
"So today, more than a century on from the 'entente cordiale' let us celebrate our own 'entente chaleureuse'", May told those gathered, using the French word for warm.
Macron declared the day's work a "full roadmap for the coming years".
The UK-France summit came as Britain tries to strengthen bilateral ties before leaving the European Union in March 2019.
The French flag was raised over the military base and the French national anthem played out for the arrival of May and Macron, who were greeted by a guard honour and a flypast of two planes.
They earlier visited the Michelin-star Royal Oak pub in May's Maidenhead constituency, where they had a "convivial" lunch together according to a British source.
While Brexit was not scheduled for formal discussion, Macron said Britain's decision to leave the European Union would lead to some "short-term uncertainties".
Macron also said that Britain could have "no differentiated access to financial services" if it decides to leave the European single market.
Otherwise, Britain would have to pay into the EU budget.
"There shall be no hypocrisy in this respect... otherwise we would destroy the single market," he said.
- Helicopters to Africa -
The French president stressed that the new border agreement was a bilateral accord, separate from any EU divorce deal, aimed at managing the sensitive of immigration as hundreds of people continue to camp out in Calais.
The two countries currently abide by the 15-year-old Treaty of Le Touquet, which permits immigration checks within each other's borders.
The new treaty signed at Thursday's summit was intended to complement the 2003 deal, according to French officials.
In addition to more funds from Britain, the two sides agreed to "improved treatment" of child refugees which Macron said would see their paperwork processed within 25 days.
The British prime minister also committed to sending Royal Air Force (RAF) helicopters to a key French counter-terrorism operation in Mali.
The deployment of three RAF Chinook helicopters to provide logistic support to French troops tackling jihadis across Africa's Sahel region is part of broader counter-terrorism and military efforts there by the UN, the EU and the African Union.
It is seen as particularly significant as France is lacking in such capabilities and Britain's commitment could mark the start of a longer-term deployment in the region.
"Since the last UK-France summit we have seen appalling and cowardly terrorist attacks in both our countries, in which British and French citizens have died side-by-side," May said.
France in turn has agreed to commit troops to the British-led NATO battlegroup in Estonia in 2019.