[universalgrl]

According to the Visual Signalling Pam No. 2 Semaphore flags may be white with a blue horizontal stripe or all blue depending on the nature of the background.
Flags are 2 ft. square and the flag poles 3 ft. 6in. long.
Under average conditions in England, with the aid of a telescope, flag signals can be read at a distance of three miles
For some strange reason flag signals did not work worth a dam at night.