Founding president of the Singh Sabha and agent of Maharaja Duleep Singh; 1837-1887
Thakur Singh Sandhanwalia
A relative of the Lahore royal family, Thakur Singh Sandhanwalia became the first president of the Sri Guru Singh Sabha in 1873. He later led the campaign to restore Maharaja Duleep Singh and passed away in 1887.
The Singh Sabha
Born in 1837, he worked as an extra assistant commissioner at Amritsar and sat on the Golden Temple managing committee. After four Sikh pupils announced their conversion in 1873, he called the meeting that founded the Singh Sabha and led it for a decade. The government later took his post away and put his estate under a court of wards.[EoS][EoS]
The Duleep Singh cause
Images

Thakur Singh Sandhanwalia, centre, with his sons Gurbachan Singh, Narinder Singh and Gurdit Singh, and attendants standing. The description on Commons, quoting a family member, places it before he left for England in 1884 to meet Maharaja Duleep Singh.
Unknown photographer, About 1884. Public domain. Source