New York-born Alfred H Caspary was a secretive man. "Cas" to his friends, only after his death in 1955, aged 77, was it revealed that he was in fact the "Pacificus" who had earned a standing as one of the finest stamp collectors and investors in the world, with an appetite for owning only the very rarest and most valuable specimens.

But even during his lifetime, Caspary had a reputation as one of the leading philatelists around. In addition to being a member of the New York Stock Exchange for 50 years, Caspary found the time to establish the Philatelic Foundation and advise the Committee of the Royal Philatelic Society in London.

The break-up of Caspary's collection following his death is one of the most revered set of stamp auctions in history. Between 1955 and 1958 the HR Harmer auction house achieved record sales for many of the leading specimens, which included an amazing collection of US postmaster provisionals, carriers and locals, as well as Confederate postmaster provisionals.

An 1861 Confederate postmaster provisional

Caspary collected stamps from all over the world. One of the leading non-US lots in the HR Harmer auction was an 1854 4-anna red and blue from India, which portrays the inverted head of Queen Victoria. It achieved $1,150 in 1958.

He also had an enviable selection of early German state stamps, what stamp expert George Sloane called "the finest Hawaiian 'Missionaries' on covers", and an excellent collection of Jamaican issues.

Writing in the Stamps publication in 1955, Sloane explained that Caspary was the "prominent Eastern collector", often referred to in the US philatelic press, when he wasn't using his Pacificus moniker.

Such was Caspary's standing among his peers that his signature was photographed and inserted into the Roll of Distinguished Philatelists in 1952, when he was too ill to make the trip to England.

Both philatelist and philanthropist, Caspary donated $3.5m to the Hospital for Special Surgery in New York State.

Caspary was inducted into the American Philatelic Society Hall of Fame in 1977.