The bishop mark was first introduced in 1661 to show the receiver of a letter the date on which it was received by the post and to ensure that letters were not delayed in being despatched. These marks were all struck in black ink, usually on the rear of the letter.
The first type, (illustrated above), was in use from 1661 until 1673. The diameter of the circle was 13mm and the letters were serifed.
In 1673 a new type was brought into use which had a diameter of between 13 and 14mm. The type used from this point was san-serif and this continued in use until 1713.
In 1713 larger handstamps were introduced which ranged in size from 14 to 20mm. The layout of these was also changed, with te mounth appearing at the base. This type remained in use untill 1787 when it was replaced by the double cirle type.