This perfin along with a special cancel was used on a cover in 1984 by the Polish Scout Association in Great Britain to commemorate the fortieth Anniversary of the Warsaw Uprising.
The stamp is part of a set of five issued for the Bicentenary of the Mail Coach Service. The stamp was perfined in two lines. The top line is the letters A K and the bottom the numbers 44. The two letters A K were used on a canceler during the uprising in the Warsaw Ghetto.
The A.K. NA BARKYKADACH in between the rings in the cancel means Polish Home Army barricade. The numbers between the lines in the center 12-8 9.44 represent the date August 12, 1944 and this is the meaning of the second line of the perfin. The j with the date is for the barricades J which were located at the Szpitalna Street Post Office.