LONDON — Reaching for a role beyond his birthright as the monarchy’s spare, Prince Andrew took on one of the British government’s most outward-facing posts: trade envoy.

From 2001 to 2011, Andrew Mountbatten-Windsor, as he is now known, hopscotched the globe not as a royal but as an official representative for trade and investment, courting presidents, ministers and chief executives and cooking up deals that at times made his family cringe.