Found in Sweden.

The card was addressed to be sent back to James Hargreaves, Bray's future father-in-law.

The Daily Graphic was a mass circulation newspaper in the Edwardian era and in 1907 it sponsored a balloon flight, as an advertising venture. It printed hundreds of miniature booklets giving details of the flight and advertising the Daily Graphic. The aviators planned to jettison these booklets en route as ballast, in the same way that earlier balloon pilots had jettisoned sand to maintain the height of the balloon. The coal-gas filled balloon, named Mammoth, took off from Crystal Palace, London at 5 pm on October 12th 1907, with a crew of three and 15,000 postcards. It drifted for 20 hours and 30 minutes over the North Sea and Denmark, eventually crash landing near the village of Brackau, near Mellerud, in southern Sweden. The crew escaped unhurt but the balloon careered on for a further 30 miles, scattering its load of postcards over a considerable area. Some cards were found and forwarded to the addressees from Tosse, where the balloon eventually came to rest, but the majority were recovered over a period of several weeks by the Mellerud schoolmaster, Mr Mickow, who had played host to the aviators when they arrived at his door after the balloon’s crash landing.

Source: www.warwickandwarwick.com

This may have been the only unofficial card to be carried on the flight.