As regular readers will know, Royal Mail will not announce the programme of stamp issues for 2026 until at least Christmas, and probably not in detail until shortly before the first issue in January.
I've had a quick glance at Wikipedia for British events in 1926, although it is not always centenaries (or multiples of 25/50 years) which are marked nowadays.
I can't see the General Strike featuring and not the birth anniversaries of Kenneth Williams and Ernie Wise.
The Imperial Conference was held in 1926 which led to the Balfour Declaration which "accepted the growing political and diplomatic independence of the Dominions in the years after World War I ... determining that they were autonomous Communities within the British Empire, equal in status, in no
way subordinate one to another in any aspect of their domestic or
external affairs, though united by a common allegiance to the Crown, and
freely associated as members of the British Commonwealth of Nations" - and hence the formal use of the term Commonwealth.
If we do see any stamps for the foundation of The Commonwealth, I can see the Commonwealth Stamps Opinion blog will be very busy!
Alas we are more likely to see more stamps for Winnie The Pooh, it being the centenary of the book's first publication.
Other notable events from that year were the foundation of what became the Council for the Preservation of Rural England, and the establishment of the first air (and hence airmail) route to South Africa by Alan Cobham. Both very worthy of commemoration - which is probably why they won't be included.
Suggestions by email only please to ian@norphil.co.uk, only one per person unless I prompt you for clarification or expansion.
Results
and comparison with the actual programme in due course. The exercise
ends when the programme is announced - please don't leak it if you see
the calendar in a post office, it won't be published here.
NOTE: just for context, the following countries have already announced their part of the annual, preliminary programmes for 2026. In no particular order:
Slovakia (in June), Belarus, Germany, Poland, Russia, Latvia, Moldova, Bosnia Herzegovina, Czech Republic, Switzerland, Belgium, Greece, Hungary, Guernsey, USA, Jordan, Montenegro, Hong Kong, Croatia, Åland,