“…Peregrine Wilson's second attempt at prospecting in Sudan fared no better than the first, and his concession in the Tokar region expired in 1905 because, though the prospecting engineers found 'black graphite material', it turned out be a type of coal with no value as a fuel. 36 The concession held by W. T. Preston (the Dongola concession) expired in 1906 after the prospecting work carried out in the winter of 1903-04 showed that such deposits of gold as there were present were of 'no value'. The Sudan Exploration Company's concession was prospected by John Taylor and Sons the mining engineers to no avail and the concession was surrendered in April 1906.…”