Complex sentence: In 2011, the British Royal Mail launched a commemorative stamp range based on the Anderson series; among the items was a mini-sheet of lenticular stamps bearing holograms of "Thunderbirds 1", "2", "3" and "4".
Split into simpler sentences: In 2011, the British Royal Mail launched a commemorative stamp range based on the Anderson series. Among the items was a lenticular mini-sheet of stamps with holograms of "Thunderbirds 1", "2", "3" and "4".