 In December 1863 Sanderson accompanied Lord Wodehouse to Berlin and Copenhagen on his special mission during the Schleswig-Holstein crisis.Early in his career he crossed paths with Lord Stanley, later 15th Earl of Derby.Sanderson became Stanley's private secretary in July 1866 and left an impression on Stanley, who described him as 'the best of the juniors' on exit from office, after Benjamin Disraeli's first government fell in the 1868 December General Election.