Before the violation of the treaty of London, one of the main debates regarding the British position to war in Europe is concerned with the terms of the British obligation to the french. Knowing this did the french move their fleet, forcing the British to honor any agreement made previously.
It's very uncharacteristic for me to post such a short answer but I'm not sure how I could really expand on this in any further way. Basically as French and British planners worked together they determined that the French would put the bulk of their fleet in the Mediterranean and basically deal with the weaker Austro-Hungarian navy and potentially the Italians while the British would handle the North Sea and the Channel with their much larger, more powerful fleet against the more potent German threat.
I've never come across the concept that the French moved their fleet to leave an exposed channel and thus force the British into the war. It was a mutual agreement between the two basically divvying up responsibilities for their respective navies w.r.t. their strengths in the event of a general European war. Once the war would begin this would be formalized with the French gaining full command of the Mediterranean theater and even gaining control of a few British ships while also gaining access to British (and later Italian) ports.
The First World War: Volume I: To Arms by Hew Strachan