Today's theme for Sunday Stamps is Unusually shaped or oversized stamps. I am sure I have a lot of unusually shaped stamps (for instance). But I wished to show the last ones I received on a letter from Laura (the UK). They belong to this series issued by Royal Mail on 6th October, 2013. What amazed me the most is that, at first sight, you don't perceive they are unusually shaped!
Update: I had also received this one belonging to the same series.