1998 - Spectator - The Americans gave up supplying gold on demand to other countries' central banks at £35 an ounce when their fair-weather friends from London threatened to turn up and clean them out.
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a credit card
This phrase comes from the advertising slogan…. Access your flexible friend.
a friend at court
a person in a position to use influence on your behalf
friends in high places
people in senior positions who are able and willing to use their influence on your behalf