Donald Trump has formally signed an executive order making parts of the new UK-US trade deal official.
The order, the first step in actioning the new deal, will see the US allow 100,000 UK cars into the country with a tariff of just 10% as opposed to the 25% previously imposed.
A similar arrangement with regard to steel and aluminium is expected to be introduced in due course.
Sir Keir Starmer, the BBC reports, hailed it as a "very important day" for both nations.
It is hoped the deal will go some distance to shield businesses in the UK from the impacts of Trump's global tariffs.
However, the agreement does still include a 10% tariff on the majority of UK goods and does not address the charges on steel exports to the US.
Announced last month, the trade deal was the first struck by the White House since the sweeping global tariffs were introduced.
Trump introduced the levies earlier this year in an effort to boost domestic manufacturing, but they have sparked market turbulence around the world.
FTSE 100
The UK's flagship share index, the FTSE 100, was down 32 points at 8,831 shortly after opening this morning.
Brent crude oil futures were up 0.68% at $72.93 a barrel.