In this position he earned a reputation as a politician of thorough straightforwardness and grit, and as one who would maintain British interests independently of party; and he shared with Mr Asquith the reputation of being the ablest of the Imperialists who followed Lord Rosebery.
When Sir Henry Campbell-Bannerman's cabinet was formed in December 1905 he became foreign minister, and he retained this office when in April 1908 Mr Asquith became prime minister.
When Mr. Asquith formed the first Coalition Ministry in 1915, he included Mr. Henderson in the Cabinet as President of the Board of Education, and also adviser of the Government on Labour questions arising out of the World War.
But, in fact, it failed; and the friction engendered between the First Lord and the First Sea Lord was one of the causes which drove Mr. Asquith to invite the Unionists in May to join in a Coalition Government.
The British government (the Asquith cabinet) came to the conclusion that another expedition against the mullah would be useless; that they must either build a railway, make roads and effectively occupy the whole of the protectorate, or else abandon the interior completely.