Shown below is an example of the 1 Penny (red) issued for Great Britain in 1841. The stamp had a small crown watermark.The earlier issues of the 1 Penny stamp had letter only in the lower corners of the stamp with the Maltese cross in the upper corners, no identifying plate number and in addition the paper showed a "blueing". This blueing is thought to be the result of prussiate of potash present in the printing ink or paper that altered the colour of the paper when it was damped for printing. Many of the earlier issues can now only be dated by the watermark and type of lettering in the lower corners. Four types of alphabet were used in the lettering. The first used smaller letters that gradually became larger and bolder in subsequent issues of the stamp. The watermark on this example is very difficult to see without a strong light behind the stamp. However the view of the back of the stamp with give an indication of the blueing of the paper.