First Stamp
The first British postage stamp--and the first adhesive stamp printed ever--was what is now called the "Penny Black." The 1840 stamp has a profile of a bust of Queen Victoria with "Postage" at the top and "One Penny" at the bottom.
1950s
Many 1950s British stamps say "ER," "Postage" or "Postage Revenue" and have a profile of a king or queen's head.
Modern Stamps
Many modern British stamps, from the 1960s onward, have a small silhouette of the queen's head in the corner and no country name printed on the stamp.
Denominations
British stamps have denominations in pence and shillings (a small d and a backslash mark, respectively) or British pounds and portraits of a king or queen but no country listed.
Pounds &Pence Only
Britain does not use the Euro as its currency and so its stamps do not have the Euro symbol on the denomination; some European stamps may show two currencies, one being the Euro.