Although I'm no lover of Blair/Brown, the actual figure left by the last government was £700 billion...which was mainly caused by spending on Education, Health and Welfare (for the sick and disabled despite Daily Mail headlines focusing on the 0.001% of con artists, most of whom were brought to book, hence the headlines)...
The current shower have managed to raise that to the figure you quoted of £1.5 Trillion (i.e. they doubled it in 3 years), they managed to do this despite reducing funding to health, welfare and education, despite reducing funding to just about everything and allowing the growth of parasitic companies like ATOS and OneConnect, both of whom have a mandate to screw people over (allegedly
)...
AND they have increased the cost of everything they could think of and allowed foreign power companies to rob its electorate blind in the name of Mammon.
They take money in bedroom tax from pensioners and the disabled whilst allowing companies like Amazon to avoid paying tax by lack of modern thinking and poor legislation.
We have tory MP's laughing and joking about foodbanks and a minister for education who thinks schools should be run by Mr Chips and Joyce Grenfell. They have stifled the economy despite advice from almost every single economist on the planet. We give foreign aid to countries with space programs, (something we can't afford ourselves), whilst removing aid from our own by reducing the number of firemen, policemen and hospitals.
And before you use the stock 13 years argument..yes Blair/Brown were screw ups, liars, warmongers, wasters, pension thieves, muppets and generally made a right mess of things..but this incumbent lot are systematically destroying every single good thing that was ever created in this country and increasing the debt of every single man, woman and child with their insane policies.
If you seriously believe that the current crop of Conservatives are working for the good of the many, you have a real problem with your logic.