In 1956 in Hungary happened a popular uprising against the current government, installed by Soviet forces. The uprising lasted 12 days and left thousands of people killed and wounded. Almost a quoter million of Hungarians fled into the exile.
USSR invasion and occupation of Hungary left to an international condemnation. At the 1956 Summer Olympics in Melbourne, the Soviet handling of the Hungarian uprising led to a boycott by Spain, the Netherlands, and Switzerland.
Spanish government issued a serie of 6 stamps, with surcharged collected sent to a fund, helping Hungarian children.
Stanly Gibbon’s catalogue sets the price for the whole set at 29.95 GBP.
Link to the set in MyCollection: https://allcollect.online/product/spain-1956-hungarian-children-relief-s1263-1268-mnh/