The Prime Cabinet officer insisted the updated immigration agreement would “work in the best regards of both France and the UK”.
UK officials said the cash would go towards high-tech kit such as carbon dioxide visual display units and heartbeat monitors to find stowaways hidden in vehicles bound for Britain.
The hard cash will also be spent on more traditional security measures comparable to fencing and new CCTV systems to prevent ports like Calais tasteful what Mr Macron has branded a “back door to Britain”.
Part of the sum make go towards relocating people away from Channel ports in an essay to stop another migrant camp like the “Jungle” from body as it did in Calais in 2015.
BREAKING: Britain is to pay France £44.5 to pay for border surety
The commitment forms part of an updated immigration treaty agreed between Mrs May and Mr Macron skilled in as the Le Touquet agreement.
The treaty allows Britain to carry out its border inspects on the French side of the Channel but has come under fierce criticism in France because some signify the deal is unfairly weighted in the UK’s favour.
Announcing the agreement at the Royal Military Academy Sandhurst, this evening, Mrs May bid the UK and France “remain committed” to the principles of the treaty.
She said: “Today we include agreed additional measures which will work in the best avocations of both France and the UK, increasing the effectiveness of our cooperation.”
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Mrs May and Mr Macron look on as the updated agreement is endorsed
The French President has been in talks with Mrs May throughout the day during his at the start visit to the UK since becoming president in May last year.
The UK has already foiled up more than £100million for additional security in Calais on the last three years.
But the investment has seen the number of people attempting to document Britain illegally fall dramatically, from some 80,000 in 2015 to well-deserved over 30,000 last year.
However, Mrs May’s decision to cave into French requests has already been poorly received by some of those in her own party.
Quits before the treaty was formally agreed this afternoon, Tory MPs were criticising the PM.
Christopher Chope, a Middle-of-the-road member of the Commons home affairs committee, said: “We keep handing one more time money for security and France keeps coming back for more. Ample is enough.
“They keep holding us to ransom. It has been suggested that this is a charge we need to pay for a trade deal with the EU but it certainly raises a lot of questions.”
Andrew Bridgen, Tory MP for North West Leicestershire, ventured: “We should send the bill to Angela Merkel, who invited the world into a borderless Europe.”
And as element of their agreement, Britain could also commit to taking innumerable child refugees from France as part of its commitment to resettle 480 alone children under the Dubs scheme, the Press Association has reported.