This is a Mauritius 1930 Philatelic Cover, sent from Mauritius to England on March 7, 1930.
What makes this cover interesting is the usage of the Great Britain SG 434a, the 1/2d Green Watermark. It's sideways, and RARE on cover. Also worth noting is the CANCELLED SHIP LETTER marking, as well as the GPO Post Office dated 3/7/1930.
Ex Ibbotson.
This item is over $100 USD so I will ship it using Priority Mail in the US, and Registered Mail overseas. This is to ensure that it reaches you in a safe and timely manner, and includes tracking!