DCP23 wrote:
http://cjoint.com/?jvrd1QgqRX

This is a British Guiana stamp with an overprint "Marine Detatchment", which
neither Scott nor Stanley Gibbons know nothing about.

Please help.

Googling on "marine detachment" "british guiana" (including the quotes)
finds a "presumably" explanation at
http://www.dave.studd.btinternet.co....anamarine.html and several other
hits (some of them broken) which provide further information and say
that these stamps were prepared but not issued.

Chris