Great British George 5 Stamps - Issued 1911 to 1936
The Reign of King George 5th is really the gem for specialised stamp collectors. There are a huge array of shades (see my links on each Specialised George 5 section for their Specialised Colour Guides), watermark variations and errors for specialist collectors. For me though, the Reign contains the most beautiful stamps ever issued - Seahorses.
The first George 5th stamps were not ready for issue until June 1911, over a year since his accession and then only the ½d and 1d values. It would take yet another year before any of the other values were ready. Hence the reason why some values of Edward 7th continued to be produced until 1913.
The first stamps were the Mackennal (Downey Heads). For what is in essence a set of three stamps (by this I mean clear and easily seen differences), the variations available in shades, errors and watermarks is amazing.
The second series issued were the Royal Cypher. These are the jewel in the crown when it comes to shades for specialists. The range of shades is fantastic. (Please go to my George 5 specialised royal cyphers image page to see what I mean). My listing is per Gibbons specialised Volume 2 and this list can be expanded on beyond that and is by many collectors. A lot of the shade variations were due to a lack of ink during the war period.

Block Cypher was next, mostly the same designs and values as the royal cypher set, but with a different watermark. Again there are some nice shade variations available.
The Photogravure series completes the low value definitive issues.
Then we have the high values, better known as the Seahorses. Primarily two designs printed by 3 different printers, each with their own characteristics, again with some wonderful shade variations. As I stated earlier, these stamps to me are the most beautiful ever issued. The design is just fantastic. Maybe I yearn for Empire and was born too late, but they just ooze a time when Britannia truly did rule the waves!
The most significant thing about George 5th reign as far as stamp collecting is concerned, is that it contained the first Great British Commemorative issue, The 1924 Wembley Exhibition. This was followed a little over a year later by the 1925 set and a further two commemorative sets were issued later. Only 4 sets in 11 years, now there’s a thought! It also saw the introduction of the first Postage Due stamps.
One final thing about George 5th that must be mentioned is that he was an avid stamp collector. This was to such an extent that it really is down to his enthusiasm that the Royal Philatelic Collection of Great Britain and the Commonwealth is without doubt by far the best collection of its kind in the world.