It's impossible to pick apart the statistics to remove macro events like that, or to determine what was/wasn't within reasonable control of the government at the time hence querying it.
I assume you know how to interpret those graphs beyond just the bigger number = bad and then zoom in on a period that shows labour = low, tories = high and pretend a global financial crash had no impact on things..?
I'm happy to be educated, I just see a graph that I see spikes on what happen to correlate with my recollection of global events and question the correlation your premise is formed on whether it is down to global events and somewhat outside of government control or if you knew what policies where enacted that you can attribute to the data that support your premise.
here's the Governments overlaid (red = lab, blue = tory, green = coalition, purple = global event)
I mean, global event certainly correlates with all the deficit peaks, but then it's a crapshoot as to which party was in when we managed the small surpluses..
I'm no expert, hence asking.