Why did the Royal Geographical Society support John Hanning Speke’s later expedition?

The Royal Geographical Society supported John Hanning Speke’s later expedition because he was widely celebrated in London as the first European to reach Lake Victoria, which he correctly identified as a source of the Nile.1

Following his initial return from Africa, Speke was lionized by the public and the scientific community, leading the society to provide him with the necessary funding to return to the continent to further map the region and confirm his findings. While his conclusion regarding the lake was disputed by his former partner, Sir Richard Burton, and others in England, the society honored Speke for his exploits and continued to back his efforts to resolve the long-standing geographical mystery of the Nile's origin.12