Celebrating 50 years of Royal Mail Special Stamps 2015 marks the 50th anniversary of Royal Mail's modern Special Stamp programme, which celebrates the UK and our national character. The oak stamp was part of the Tree Planting Year Special Stamp issue in February 1973. In Sherwood Forest there is a Major Oak tree which is thought to be over 1000 years old and was voted England's tree of the year in 2014.