The question of Beltwood House's History has been going around for some time. Five minutes on the internet has thrown up some interesting information that I wanted to share.
The first thing was to see what Southwark planning thinks they have here:-
This document http://www.southwark.gov.uk/Uploads/FILE_41458.pdf
states the following:
To the southeast, Beltwood House is located between Sydenham Hill
and Crescent Wood Road, within attractively landscaped grounds. This
large detached house is listed grade II, and dates to c.1855 –1863. It
was remodelled in c.1895. It is thought that the building was designed
for Edward Stanton by Barry and Barry, architects to Dulwich College.
The house is of two storeys, rendered with a slate hipped roof, with a
bracket cornice and a frieze with paterae and two rendered chimneys.
Externally the elevations contain a variation of elements including
Adamesque swags to a pediment with oculus above three central
windows supported on pilasters. The southwest or entrance front has
two curved bays to the first floor with mullioned and transomed leaded
lights, between which is a large porch with round headed cornice and a
pair of Roman Ionic columns to each side containing an open
Armed with this information I looked in Wikipedia for Edward Stanton. The following person is one of two recognised there....
And guess what? You've all heard rumours of the German Ambassador living there? Well he was Chargé d'Affaires to the King of Bavaria at exactly the right time. Bit of a co-incidence if you ask me.
The entry is as follows:
General Sir Edward Stanton, RE, KCB, KCMG (19 February 1827 – 1907) was a British officer and diplomat.
Edward Stanton was the son of William H. Stanton, Esq., of Stroud, Gloucestershire. Born on 19 February 1827, he was educated at Woolwich Academy. He was commissioned as second lieutenant in the Royal Engineers on 19 December 1844. He served in the Crimean War, which was fought from 1853 to 1856 between the Russian Empire on one side and an alliance of France, the United Kingdom, the Kingdom of Sardinia, and the Ottoman Empire on the other. From 1856 to 1857, he served on the boundary commission that determined the Russo-Turkish borders.
He was appointed Consul-General in Warsaw, Poland on 7 December 1860, Agent and Consul-General in Egypt on 15 May 1865, and Chargé d'Affaires to the King of Bavaria on 10 May 1876. During his visit to Egypt, English author and poet Edward Lear described Sir Edward Stanton as "very good-natured". Sir Edward Stanton retired as a general in 1881 and received a knighthood the following year.
In 1862, Edward Stanton married Lady Margarette Constance Stanton. He was a relative on her mother's side of the family. His son Colonel Edward Alexander Stanton (1867–1947) served in Egypt at Omdurman, was Governor of Khartoum from 1900 to 1908, and military governor of Haifa (the Phoenicia Division of Palestine) from 1918 to 1920.
In addition to his British honours, Sir Edward Stanton was a Knight of the French Legion of Honour.
In the absence of any other information I think we might have a match.