British billion

Question

I found that in British billion = million million, that is 1,000,000,000,000, but I also found in this news that UK made a £1.2 billion trade deal with India, but that number is incomprehensible. According to wikipedia, UK's nominal GDP is $2.849 trillion, with trillion also = million million, UK made a deal about 50% of its annal GDP, is this really what is happening? Or in this case UK government uses billion in US billion?

Answer 1

A "billion" is "one thousand millions" both in BrE and AmE. Here is how the term evolved and its curent usage:

• In British English, a billion used to be equivalent to a million million (i.e. 1,000,000,000,000), while in American English it has always equated to a thousand million (i.e. 1,000,000,000). British English has now adopted the American figure, though, so that a billion equals a thousand million in both varieties of English.

ODO

Billion : etymology

• 1680s, from French billion (originally byllion in Chuquet's unpublished "Le Triparty en la Science des Nombres," 1484; copied by De la Roche, 1520); see bi- "two" + million. A million million in Britain and Germany (numeration by groups of sixes), which was the original sense; subsequently altered in French to "a thousand million" (numeration by groups of threes) and picked up in that form in U.S., "due in part to French influence after the Revolutionary War" [David E. Smith, "History of Mathematics," 1925]. France then reverted to the original meaning in 1948. British usage is truer to the etymology, but U.S. sense is said to be increasingly common there in technical writing.

Etymonline