The London publisher who first signed up Harry Potter author J.K. Rowling is banking on a new franchise, about a boy archaeologist, the Reuters news service reported.

Roderick Gordon and Brian Williams were signed by Chicken House publisher Barry Cunningham after he tracked down an early version of their book, Tunnels, which was self-published.

Tunnels features a boy archaeologist, merciless villains, a lost world and an extraordinary journey to the center of the earth.

The authors originally met at university but went on to follow very different careers, one as an investment banker, the other as an artist.

They got together when Gordon was made redundant from his job in corporate finance. He then sold his house to self-publish a limited-run edition of Tunnels.

Cunningham heard of their success and signed the pair up for a series of fantasy tales seen through the eyes of 14-year-old Will Burrows and set in a hidden world deep below London.