When my wife and I moved into the district last year we were intrigued to learn that our house was one of nine 1930s dwellings built in the grounds of a former large Victorian villa called Adon Mount.  The mansion and its owner remained a mystery until we joined the Dulwich Society and bought a copy of Who Was Who in Dulwich: 100 Notable People, edited by Bernard Nurse. In this I discovered a reference to Adon Mount under the entry for James Henderson, who had not only started the Glasgow Daily News (the first penny daily newspaper in the UK), but had also founded the South London Press.
After further research I discovered that Henderson was born in Laurencekirk, near Montrose, Scotland, in 1823, the son of a saddler.  At first he worked for his father but later pursued a career as a journalist. Moving to Glasgow he worked on Scotland's first daily newspaper, the North British Daily Mail, before starting up the Glasgow Daily News. Then, after a brief spell at  the Leeds Express and the Manchester Guardian he set up the Weekly Budget (1861) which was so successful (by 1865 it had the largest provincial circulation of any newspaper in the UK) that he transferred his offices to London. Here he began publishing an increasing number of newspapers and children's journals as well as books and pictorial postcards. Amongst these were the South London Press  (1865), the Evening Mercury (1868, the first ever halfpenny evening paper in the UK), Young Folks (1871, which first serialised Robert Louis  Stevenson's Treasure Island, The Black Arrow, and Kidnapped ), and  Funny Folks (1874, the world's first modern 'comic').
Such was his success that in 1865 Henderson built an imposing villa for himself and his family on Primrose Hill (now Dawson's Hill), a 250-foot-high promontory which had been the site of a Bronze Age burial mound and a Roman fort, and was positioned on a ley-line (it had earlier been called Ladlands).  When it was built Adon Mount was mostly surrounded by fields. Overhill Road  and Mount Adon Park did not exist. Nor did Lordship Lane railway station (1865),  Dulwich Park (1890)  the old Fire Station (1893)  and Dulwich Library (1897) and there were still kennels (for the hounds of the Surrey Hunt) on Dog Kennel Hill itself.  To the west was the old toll gate at the end of Court Lane, and  to the east was Dawson's Brick & Tile Manufactory (after which Primrose Hill was later renamed).  
At first Henderson's villa was called 'The Mount, Friern Manor Hill' (another name for Primrose Hill) and this was the publisher's address which appeared on copies of the South London Press until 3 March 1866 when it changed to 'Adon Mount, Dulwich'.  'Mount' was a common name for a hilltop residence (the original home of the tea magnate Fredrick Horniman nearby was Surrey Mount), and  'Adon' is Hebrew for 'Lord God' (Henderson was a strict Presbyterian). 
With the coming of the railway link to Crystal Palace and the opening of Lordship Lane Station the area around Dulwich became very popular and there was a spate of house-building for City commuters. In 1871 there were only about 4000 residents in Dulwich but in the following decade 5000 houses were built. According to Brian Green's Dulwich: A History (2002)  ' Almost all of East Dulwich was built in a single generation, between 1875-1900.'
Henderson himself was bitten by the property development bug and not only began acquiring neighbouring houses but also started building new ones on the surrounding land  to form the Adon Mount Estate. He even seems to have considered letting Adon Mount itself, as an advertisement in The Times (27 May 1879) bears witness. (Another reason for this may have been local disturbances - according to Brian Green, in 1878 the police removed 200 horses and  45 donkeys from a large gypsy encampment nearby on the current site of Dawson's Heights.)
Amongst the properties Henderson acquired were three mansions in Overhill  Road – Rock Bank, High Bank and the Red House (home of Henderson's oldest son, George). Of these, the first two were semi-detached and (after a period as the  Rockbank Hotel), still stand today as blocks of flats. The Red House was later demolished and replaced in 1936 by nine dwellings  (Nos 170-154) – including ours - though two surviving large brick gateposts outside Nos. 176-172 may have marked its original  entrance.
Henderson also acquired Gothic Lodge (home of his brother William Cream Henderson and later of William's son) in Lordship Lane on the corner of Upland Road (now demolished). In addition, in 1882 he built two new detached, double-fronted houses  - Oak Tree Bank and West View Bank  - on Lordship Lane on either side of the opening to Mount Adon Park. These were also advertised for rent in The Times (25 April 1883).
In addition, Henderson built Mount Adon Park itself. Named in 1881, the road cut through the field between Gothic Lodge and Adon Mount and originally consisted of 10 houses. Of these No.1 (home of his second son,  Nelson) was a detached double-fronted residence, Nos 2-7 were semi-detached, and Nos 8-10 were detached (his third son, Winfred, lived at No.8).  
Though No.1 was later demolished and replaced by modern terraced houses,  the original Nos. 2-7 remain on the north side of the road (now numbered 25-49) and it is assumed that Nos 8-10 were the buildings which now form  369-373 Upland Road  (these were built after 1896).  The house currently numbered as No.50 Mount Adon Park does not seem to have been part of the original Adon Mount Estate.
Henderson became a significant figure in the area and was President of the Dulwich Liberal & Radical Association. He even stood as a Liberal candidate for Dulwich in the parliamentary elections in 1887,  supported both by former Home Secretary Rt Hon. Hugh Childers (a cousin of Erskine Childers) and the celebrated journalist and MP T.P.O'Connor (founder of the Star and other papers). However, he was defeated by the Conservative John (later Sir John) Blundell Maple (Chairman of the famous furniture company).
 Four of Henderson's eight children were born at Adon Mount. His two oldest sons, George and Nelson, both attended Dulwich College (and Nelson even played rugby for Scotland). Both, together with his youngest son Winfred, worked for the family firm and in about 1900  they  took over the business.  James himself retired to Worthing, Sussex, in about 1905. He died there on 24 February 1906. 
In 1907 the family sold the South London Press to concentrate on magazine, comics, postcard and book publishing. However, in 1920 the magazine and comics titles were taken over by Alfred Harmsworth's Amalgamated Press and the rest of the business also seems to have been wound up at this time. Adon Mount was sold to property developers in 1910 who demolished the villa and  built in its place the 18 gabled houses which form the south side of Mount Adon Park today (Nos.6-40).
James Henderson was buried in Camberwell Old Cemetery close to Adon Mount. His grave, long forgotten and grassed over, has now been discovered after much research, and it is hoped that it will soon be restored to its former glory, as befits the final resting-place of one of the great pioneers of popular journalism.