Ford has been number one in the UK for decades. It stopped making cars in England in 2001 but makes millions of engines and does extensive design and research there so supports the UK economy well.
The brand it has had to keep at bay for many years is GM's Vauxhall, which cannot quite do enough to dethrone it. Vauxhall makes the Astra and Astra van as well as the Vivaro/Trafic vans but that's about within Britain as design and engineering work is done in Germany.