I have found these stamps in a book that was given to me, do you know how much they are worth?
by Guy Simmons
There are two Postal Union Congress London 1929 stamps, the 2 1/2 has a crease. The two halfpenny stamps? are a different colour green, the lighter one has markings on the back as shown, it is also on thicker paper almost card, these stamps are hinged in the book.