Definition of "taipan"

Of course it was very sad, but the taipan could hardly help a smile when he thought how many of these young fellows he had drunk underground.

1922, W. Somerset Maugham, The Taipan

The British taipans stood in one sodden circle with their womenfolk, like bored officers at a garrison get-together.

1977, John Le Carré, The Honourable Schoolboy, Folio Society, published 2010, page 438