On May 6th 1840, the world's first adhesive postage stamp went on
public sale at post offices through-out Britain. The intention was to
indicate pre-payment of mail. Prior to this, most mail was paid for by
the recipient. The old system was in no way accurate, inexpensive or
reliable. Communications, were seriously hampered by the lack of an
effective system. But within 2 days of the first stamp being released,
a second stamp was issued which in effect was the double value ( 1/2
to 1 ounce weight ) of the first and also served as the 'Penalty rate'
for anyone not prepaying the postage. Like the Penny Black, the Two
Penny Blue showed a portrait of Queen Victoria and was printed in
sheets of 240 ( 12 across x 20 down ). Before the decimalization of
the English currency, one row of 12 stamps equaled a shilling and 240
One Penny stamps made an old £.

Since its very first stamp, Britain has always been the only Country
in the World, not to feature its name on postage stamps, just a
picture of the reigning monarch.

Many security devices were incorporated into this stamp, to thwart
potential forgers, such as : the use of specially watermarked paper,
an engine turned background, a super clear engraving of Queen
Victoria and a lettering system that would identify each individual
postage stamp on a sheet ( detailed above ). All in used condition.