Again, in 1914 the average PM needs to explain himself to the average Englishman much less than today. He has to explain himself to the average MPs - who are much less in thrall to opinion polls than today and who know geopolitics.
Why are you referring to the 'average PM' when we know the PM was Asquith, who was a Liberal Party man first and a man of peace second. Without a decent CB, Asquith would have had to destroy the party he loved, to do something he loathed.
Why are you talking about
average MPs, when the known members of the British Liberal Cabinet would be making the decisions. Those familiar with history know the British Liberal Cabinet of 1914 was overwhelmingly against war, with Gray and Churchill being the only pro-war exceptions. Immediately prior to the German invasion of Belgium, Asquith described the ineffectual pro-intervention speeches of Churchill as bellicose, whilst describing Lloyd George (being the notional leader of a block of seven pacifist/ non-interventionist members of Cabinet) as constructive.
The British Cabinet explicitly contemplated Belgium either not actively defending its neutrality and/or not requesting British assistance. In covert discussions with the conservatives, Churchill contemplated the British Liberal Cabinet choosing peace, even if the Germans choose to violate Belgium neutrality.
As to the man in the street, I think he did not like Germany at all, especially between 1908 and 1912. That's because of the naval arms race has gone beyond the awareness of just a few military experts, admirals and statesmen, and because of the Kaiser's mightily inappropriate interview in 1908.
The average British man on the street cared little for war, whilst the British powerful industrialists and financiers were actively lobbying against war.