The thick lavender tinted paper on Great Britain SG15 (1851 2d blue) arose as a result of variations in the paper-making process during the early 1850s, rather than a deliberate, sustained change in paper stock. This distinctive paper is, in fact, a paper variety used for certain printings, often described as part of the SG spec B1L (1d red-brown) as well.

Paper Characteristics: The paper used for this issue was noticeably thicker than the standard paper of the time, resulting in a more opaque and sometimes slightly stiffer stamp.

Lavender Tint: The lavender or lilac tint was a result of the chemicals added to the pulp during the paper manufacturing process, often intended to make the paper appear whiter, but which instead imparted a bluish-lavender tint