Do British say billion

Yes, British people do say "billion," and in modern British English, it means the same as American billion: 1,000,000,000 (one thousand million). However, this represents a relatively recent shift in British usage.

Historically, British English used the "long scale" system where a billion meant one million million (1,000,000,000,000—what Americans call a trillion), and the term "milliard" was used for one thousand million. This created significant confusion in international communications. By the 1970s, British English began adopting the American "short scale" system, where billion means one thousand million, and this became officially adopted by the UK government in 1974. Today, virtually all British financial reporting, scientific literature, and news media use billion in the American sense. You might occasionally encounter older British texts or speakers who remember the old long scale, but contemporary British usage aligns with international standards.