This two-coin set is one of the "historic" issues by the Royal Mint combining a newly released coin with a historic coin taken from circulation.
The mint says about it:
"The Royal Air Force Aerobatic Team, who are more commonly known as the Red Arrows, represent the very best of the Royal Air Force (RAF). Each member of the team goes through a series of rigorous tests before they are selected and together, they represent the excellence and capabilities of the service. Renowned for their captivating aerial displays and precision flying, the Red Arrows have flown nearly 5,000 displays in 57 countries since their inception in 1964 and first public show in 1965.
People from a wide variety of RAF roles and professions are key to the success of the Red Arrows and their performances would not be possible without "The Blues", their hardworking engineers and support team on the ground. As the public facing side of the RAF, the Red Arrows also serve as a recruitment tool for the Armed Forces, with many pilots and support staff choosing a career in aviation after seeing the spectacular displays as a child."
The modern coin in the set is a commemorative 50 pence piece featuring the Red Arrows and is in Brilliant Uncirculated grade, while the historic coin is a circulated sixpence from 1965. | 
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