In Biggles' Chinese Puzzle (short story), Estere was the Swiss manager of the Pagoda Palace Hotel in Saigon and the front man for the criminal operations of the Ching Loo organisation. At their first meeting, there was something about Estere which led Biggles to dislike and distrust him on sight. Johns describe Estere as "typical of the type", medium build, good looking in an unemotional sort of way, and as a Swiss, obviously one who knew his job. His grey eyes reminded Biggles of an Alsatian dog watching a stranger. Except perhaps for the eyes, there was nothing in this pen picture to evoke that kind of negative reaction from Biggles but then Biggles was known for his instincts.
As operations manager for the Ching Loo criminal organisation, Estere obviously was well informed by his spies and through them he had learnt that Biggles had been asking a few too many questions at the airport about Marcel's Morane aircraft. He therefore warned Biggles that Saigon was not a healthy place for people who asked questions and advised him to leave the city as soon as possible.
Earlier, an American pilot Bollard had rather indiscreetly told Biggles that Estere was a man who could use a pilot wanting to earn something on the side. Biggles dangled this before Estere but he was too cautious to bite at the first meeting.
Estere's first initial was "P." as given on the plate on his door but what it stood for was never revealed in the story. He was arrested with the rest of the Ching Loo organisation at the end and given a long prison sentence.