This perfin was used on a cover in 1985 by the Polish Scout Association in Great Britain to honor the 75th Anniversary of the Polish Boy Scout Association.
The stamp is the one penny definitive perfined in two lines. The top line is just a Z and the bottom the letters H P. These initials are for the Polish Scout Association (Zwaizku Harcerstwa Polskiego).
No canceled copy of this stamp has yet been seen, as these covers appear to have been a souvenir.