Gerhard Zucker, was obsessed with the concept of using rockets as means of carrying mail.
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"On 6 June, 1934, Zucker successfully launched a mail-carrying rocket on the Sussex Downs. Envelopes carried on this flight were franked with special ‘stamps’, created by overprinting the APEX souvenir vignettes with the inscription “ROCKET POST – First British Flight”. These stamps did not bear any indication of face value but were tied to the envelopes by a rather elaborate cancellation which showed the date and location of the ‘trial firing’ and (in tiny lettering) the words “Zucker Rocket Post – Rocket Fee Two Shillings Six Pence Paid”.