It is the very one that won the 1924 competition organised by the General Post Office & Royal Fine Arts Commission.
It is the forerunner of all those familiar red phone boxes.
With the main gates of the Royal Academy in Piccadilly closed against protestors, there was a rare chance to have a clear view of this significant phone box.
Normally with the RA gates open, this little listed building is hidden, although it does still work and is unusually clean.
The other RA phone box, which stands opposite and to the east, is a regular production version of the K2.
For in-depth information on all telephone box related matters see: www.the-telephone-box.co.uk