Bayonet from Spanish Civil War

"While clearing an Uncle's house I found this in the Attic. The markings on it say Toledo in Spain and it has a serial number on the back. Several years later I was on a holiday in Toledo and I brought this with me to a museum. They explained it was a bayonet off a rifle that would have been used in the Spanish Civil War. The serial number is probably the soldiers number but they couldn't give me any more information as to the family are the value. How it came to be in an attic in Dublin is beyond me!"