In 1941, the BBC began prefixing their transmissions to the European mainland with 'V' in morse code, a practice that was so successful they kept it up long after the end of the war. http://www.transdiffusion.org/2015/07/16/dot-dot-dot-dash

BBC 'V for Victory' tuning signal

This is Radio Northsea International Broadcasting on 192 Meters 1561 KHZ on the Medium wave (AM) band and on 9940 KHZ in the 31 Meter Shortwave band Broadcasting off the coast of the Netherlands from the psychedelic-painted Radio Ship the MV Mebo II now signing on
*Man of Action by Les Reed and his Orchestra plays*

The independent broadcasting authority since 1964

BBC 'V for Victory' tuning signal

Transdiffusion