I conceived of the event after reading the Ancestor's Tale in 2009. It was first realised in 2010 in Somerset with 40 or so friends and family.
It grew substantially in 2011 when Richard Dawkins became aware of our efforts and provided publicity and financial support.
In 2013 and 2014 he appeared in person as a speaker and has supported us ever since in its promotion through tweets and website articles.
Since 2014 the trail location was moved to London and became self financing - no longer receiving funding from the Richard Dawkins Foundation for Reason and Science.
The trail is run by a small group of volunteers -mainly members of the Central London Humanist Group, especially Steve Clapman, Damian Belson, Lucy Wainwright, Phil Walderand several others. The original London trail routes were the work of David Miller.
Important people in the planning and running of the Somerset trails (2011-2013) were Paul H, Simon F, Jo B, Mark R, Sue J, Chris K, Matt M, Kate N.
The event has also been supported by the British Humanist Association. There is also a schools version of the trail called the 4 billion year walk