The clue “18th century English statesman who was twice prime minister” most strongly points to William Pitt the Elder (1708–1778).

Who he was

  • William Pitt the Elder was a dominant British statesman in the mid‑18th century, famous for his leadership during the Seven Years’ War.
  • He is often described as having been twice “virtual” prime minister : first from 1756–1761, and again from 1766–1768, at a time when the office was not yet formally defined as it is today.

Why this fits your clue

  • He was an 18th‑century figure (born 1708, died 1778).
  • Contemporary and later writers treated him as prime minister in two distinct periods even though the constitutional title was still evolving, which is why quizzes and forum puzzles often phrase him as “twice prime minister.”

Related note

  • Another 18th‑century figure who clearly fits “twice prime minister” in the modern, official sense is William Pitt the Younger , who first became prime minister in 1783 and then returned to office from 1804 until his death in 1806.
  • However, because he is usually tagged as a late‑18th/early‑19th century leader, many trivia and quiz contexts use Pitt the Elder as the intended answer to your specific wording.

So, the expected answer for “18th century English statesman who was twice prime minister” is William Pitt the Elder.