Hello,  Let's do one more from Gibraltar,  I showed a 1949 UPU issue a few days ago.  Here is the 2d value. A lovely carmine  colour.

Some history. You know there are 4 stamps in most issues but originally it was proposed only three stamps would be in the issue.

The first international postal congress was convened in Berne, Switzerland on 15 September 1874 (although a conference in Paris had been attended by the world's major postal administrations in May 1863). On 9 October 1874 Britain and 21 other nations signed a convention, effective from 1 July the following year, which embodied the agreements reached on the reciprocal exchange and unimpeded transit of letter posts and the uniformity of tariff levels. 

To maintain this co-operation the congress instituted the ‘Union Generale des Postes’; at the following congress, held in Paris in 1878, the name was changed to ‘Union Postale Universelle’ or UPU (Universal Postal Union). 

On 16 June 1947 the head of the Polish postal administration and his country's delegate to the congress, proposed that an identical series of three stamps be issued in all countries of the Union on its 75th anniversary, to draw attention to the principle that it constituted a single postal territory.

The issue was only the second British Empire Omnibus Collection not to mark a Royal anniversary. It is also the largest Omnibus collection ever issued – featuring a total of 310 stamps from 84 different countries. The uniform (Omnibus) design is featured on most issues 

The responsibility and distribution of the majority of the stamps went to the Crown Agents in London.  The stamps were designed in Great Britain, then approved by Buckingham Palace before being printed and then transported overseas.   Some countries such as Bahrain, Eastern Arabia and Kuwait, simply overprinted the British stamps. Whereas other countries such as Australia and South Africa issued their own designs. 

Have a lovely weekend.  more tomorrow.         Michael cddstamps.com