Some Stamps which were released on 1st April
1 .The first stamps for Ceylon were issued on 1 April 1857: The stamp features a portrait of Queen Victoria and is brown in color.It is a 6 penny denomination used to send a half ounce letter from Ceylon to England.8 more stamps were issued in year 1857, all featuring the portrait of Queen Victoria.One of the 5 stamps that were issued on 23 April 1859 is considered to be the most valuable stamp in Sri Lanka.It is a 4 penny denomination with a dark pink colour known as the 'Dull Rose'
2. On 1 April 1957, twelve British stamps from the Wilding series were issued, along with overprinted high value 'castles' stamps. Later in 1957, three stamps from the British Scouting Jubilee series were issued and in 1960 a further series of Wilding stamps were issued with a different watermark. All were overprinted QATAR and the value in Indian currency.
There are many stamps which were issued on 1 April. The above is just a small part.