Protective Overprints and Underprints

My main area of philatelic interest is the protective overprints and underprints of the stamps of Great Britain during the reign of Queen Victoria.

What are Protective Overprints and Underprints?

Overprints (on the face of stamps) and underprints (on the back of stamps) were applied by firms to their own stocks of postage stamps to protect themselves against petty pilfering by staff.

When were they in use?

The majority of these overprints and underprints were applied to British stamps during the reign of Queen Victoria between about 1858 and 1882.  Two firms are known to have used the same method on stamps of King Edward VII (round about 1903-4) and George V (round about 1912).

How are these related to Perfins?

Perfins (PERForated INitials) are perforations applied to postage stamps in the form of initials or designs.  These identify the postage stamp as being the property of a particular firm to avoid fraudulent use of the stamps.  In this they serve exactly the same purpose as their forerunner the underprint and overprint.  Indeed several firms that used the overprints and underprints went on to use perfins when the post office outlawed the use of the former method of protection.

Identifying Overprints and Underprints

Stanley Gibbons currently list 72 distinct designs of underprint and overprint.  A different catalogue number is assigned to a design for each basic stamp it appears on.  A distinction is also made where the orientation of the design on the stamp differs (e.g. if the design can appear reading upwards as well as downwards on the stamp).  These catalogue numbers are designated by the prefix PP.  They currently range from:

The Stanley Gibbons Great Britain Specialised Stamp Catalogues Volume 1: Queen Victoria and Volume 2: The Four Kings dedicate Appendix 2 and 5 respectively to these stamps.   I know of a few unlisted designs (the Lowfield underprint being the most well known one) and there may well be more yet to be discovered.  Of those listed there are some I have never encountered but I have no reason to doubt their existence.