This card shows the signals used by the Gibraltar Garrison, illustrated in pen and ink with watercolour.
There is a wealth of information on this picture that helps to date it. A number of the flags shown, changed or were modified through the 19th century giving a time line. If the signals were updated immediately then a date of 1848 can be determined. The Sardinian Merchant Ship flag (28) was used between 1815 and 1848; the Sardinian Standard showing the Italian tricolour with the addition of the shield and crown was adopted on the 15th April 1848 and the Austrian Flag (20) which has the letters FR was presumably for Ferdinand Rex who abdicated in 1848. Added to this, the one year that the Naples flag changed was 1849 with the flag shown used both prior and after this date up to 1861. A number of other flags point to a mid 19th century date including the Norwegian (29) and Swedish flags (23) which show the use of both countries colours which were introduced in 1844. Other flags changed not long after such as the Venezuelan flag (20) in 1859, Ionian Islands (9) in 1862 and the East India (3) with the Company dissolved in 1874. There has been a Signal Station on the top of the Rock of Gibraltar since at least 1727 with its height lending itself well to the job. Its purpose was to identify and alert the many batteries and fortifications on Gibraltar of any approaching ships.
This card is also marked HMS Princess Royal and probably refers to the Battery of that name on Willis's Plateau. It was one of a number of batteries on the Rock and it would have been important for all of them to quickly identify the signals coming through in case action was needed. This card would have been essential to the battery for that job. It is probable that they were drawn by a member of the Gibraltar Garrison and although amateur the quality of draughtsmanship is high. This has elevated them from their original purely functional use to a decorative item that would be of interest to both vexillologists and those connected to Gibraltar. Circa 1848.