London's most famous door has not always been the sober black we know today.
For a brief spell in the early 20th century, the Prime Ministerial portal seems to have been painted a dark green.
The paint job happened on the watch of Liberal Prime Minister Herbert Asquith, who held the office from 1908 to 1916 — perhaps for this entire period.
Why the colour change was ordered is something of a hue-dunnit. One rumour points to Asquith's wife Margot, who disliked the authoritarian black. Or it may simply have gone green to match other nearby doors — bronze-green was a popular colour in Edwardian times.
In any case, nobody much cared about the switch at the time. In an age before mass visual media, the black door would have been nowhere near as iconic as it is today. The paint job seems to have been carried out with little fuss. We can't find a single mention in the newspaper archive, for example.
Imagine the commotion if the door were painted a different colour today*. It would be front page news. Editorials would refract the story through every possible angle. The paint job would variously represent a bold environmental direction, be pure tokenism or greenwash, or signal that the Prime Minister desired a fresh start. Someone would file an FOI about the cost of the paint, and whether it came from an environmentally friendly source. Shakin' Stevens would re-release his chart-topping hit.
It doesn't bear thinking about.
Much about 10 Downing Street is not as it seems. Untreated, the distinctive black bricks would be yellow. They gained their black colour from years of smog, and are now painted black to maintain appearances. The door itself is not the oak original known to Asquith, Churchill and Thatcher (this is in the nearby Churchill War Rooms). Following the 1991 IRA attack, it was replaced with a reinforced steel replica.
10 Downing Street is a building of sham and cover-up, and an all-too-easy metaphor for its inmates.
*The door arch was briefly illuminated green ahead of the COP26 talks, but that hardly counts.