Henry Clarke was Charlie's Uncle, and is consistently referred to as 'Uncle Harry' in the diaries. He was an older brother of Charlie's mother, Emily Payne (nee Clarke), and appears to have been the 'Black Sheep' of the family. He was born in Highgate on 21 November 1846. In 1861 he was recorded in the census records as working as an errand boy. Later in life he worked as a private inquiry agent; for several years he advertised his services from an address in Cockspur Street, Charing Cross, and almost certainly worked with his father, George Clarke, after George had retired from the London Metropolitan Police force in 1878. After his father died in 1891, Harry continued to work under the business name of 'George Clarke inquiry agents'. Like most private detectives at that time, probably much of the work he undertook involved divorce cases, and specifically obtaining proof of adultery. In 1891 Harry was living in London at 97 Warwick Road, together with his wife (from North Shields) and their three children (two boys and a girl aged between 5 and 20 years). In 1895, Harry was arrested and charged, together with a female accomplice, with keeping a brothel, and specifically with "unlawfully conspiring by false representations to procure Gertrude Alexandra Barrett, not being a common prostitute, to have carnal connection with Charles Wilson". In his trial at the Old Bailey, it emerged that Harry and his female accomplice were unlawfully offering their clients a service in which they would arrange for adultery to be proved, if necessary by offering themselves, or hiring others. He and his accomplice were found guilty and Harry was sentenced to two years hard labour.
In the 1901 census, Harry was recorded as being the manager at the Rose and Thistle public house, 97 Warner Road Camberwell, London. his wife Mary I.Clarke appears to have stood by him; two daughters (Eva, 15 and Catherine,7) were living with them. The licensee of the pub was recorded as being his younger sister, Loo (Catherine Louisa Clarke).
When Harry's mother, Elizabeth Clarke, died in April 1907, he discovered that he had been excluded from her will (unlike all his brothers and sisters). It appears that he challenged the will but was unsuccessful. His subsequent fate is not known.
'Uncle Harry' was a frequent visitor to the Payne household in East Dulwich.