When the US Post Office Department began developing airmail routes in May 1918. To pre-pay the relatively high rates of postage on internal airmails the Post Office issued a set of three stamps that month depicting a Curtiss Jenny bi-plane. The 6c and 16c stamps for short haul flights were printed in orange and green respectively, but the 24c pre-paying letters on the New York to Washington route, via Philadelphia, was printed in two colours – the centre in blue and the frame in carmine. The stamps were printed in intaglio at the Bureau of Engraving and Printing in Washington. Being in two colours meant that each sheet had to be passed by hand through a press twice. One sheet was inadvertently passed through the press the second time upside down, with the result that the aeroplane appeared to be looping the loop.
On the morning of May 14, the day that the stamps were put on sale, William T. Robey, a stockbroker’s clerk in Washington, went to his neighbourhood post office to purchase a sheet of 100 24c stamps. The counter clerk only had a part sheet but promised to procure a complete sheet from stock if Robey would call back later. Robey promised to return during his lunch break. Just after midday he called at the post office again and the counter clerk produced a sheet from his stock book.
The sheet which the clerk handed over the had the frames were upside down! Robey paid $24 and but foolishly danced a jig with delight.
A day or two later he took the sheet to a nearby stamp dealer who offered him $500, but Robey turned it down. Later he was visited at home by two postal inspectors who appealed to Robey’s patriotism to hand over the erroneous stamps, but he refused. No other sheets turned up and Robey was offered $10,000 for the precious sheet by wealthy collector Percy Mann, but he rejected the offer. He was convinced the stamps would fetch the best price if he tried the big dealers on Nassau Street in New York.
In the ‘Big Apple’ dwelt Colonel E. H. R. ‘Harry’ Green whose wealth enabled him to build up one of the finest stamp collections ever formed. Robey decided to approach the legendary philatelist but was chagrined to learn that Green was away from home. Failing that, he tried two of the leading dealers but neither could top the previous offer.
Back in Washington Percy Mann offered to introduce Robey to Eugene Klein, a wealthy Philadelphian businessman. Thus it was that Robey eventually parted with the sheet for $15,000, the money being put up by a consortium consisting of Klein, Mann and Major Joseph Steinmetz, President of the American Aero Club. Klein took the sheet hotfoot to Harry Green who was very happy to pay $20,000. Klein pointed out that if Green broke up the sheet he would make a handsome profit and enhance the value of the stamps he retained for himself. Green broke up the sheet and retained the unique block of eight which had the plate numbers in the margin. He then handed over the remaining 92 stamps to Klein to sell. Before doing so Klein numbered each stamp in sequence on the back, so that ever afterwards, when any of the inverts came on the market, its exact position on the sheet would be recognised.
The members of the syndicate each purchased some stamps at $250. Steinmetz took a pair, but about 1930 he split it and sold one stamp, with which he bought his wife a $1,500 grand piano, ever afterwards dubbed ‘the Proceeds of One Little Stamp’. By 1940 the going rate for an Inverted Jenny was $4,000. Five years later, when the vast collection of the late Harry Green came up at auction, his block was broken up into a plate block of four and four single stamps. One of these was purchased, for about $5,000, by the dealer Philip Ward on behalf of an anonymous private client. This stamp, number 26 in the sheet, was rather more desirable as it had a vertical guideline down the left hand side, indicating the centre of the sheet. It passed eventually to a descendant who in 1993 submitted it to the American Philatelic Foundation for a certificate. Three years later it fetched over $150,000 at a Shreves Philatelic Galleries auction in New York.