There could hardly be a more justified cause for joining the war on Britain's part, considering how the Germans handled Belgium, but were they looking for a reason to intervene beforehand? I know Germany and Britain had been major rivals, with their own naval arms race before the war and opposition in the Moroccan crises, but was their joining the war entirely contingent on the violation of Belgian neutrality?
but were they looking for a reason to intervene beforehand ... but was their joining the war entirely contingent on the violation of Belgian neutrality?
Nope to the first bit, yes to the second bit
As of July 29th, 1914, only 5 of 19 cabinet members supported going to war in support of France. It took the invasion of Belgium to rally the Cabinet, Commons, and public opinion, to supporting British intervention.