Title says it all.
It's an eye-catching statistic, but how could it be true? Well, I'm obliged to Ian for compiling a list of the 20 most marginal seats in the country, from which we need to consider the closest seven that are Tory-held.
Gower maj 27
Derby North maj 41
Croydon Central maj 165
Vale of Clwyd maj 237
Bury North maj 378
Morley & Outwood maj 422
Plymouth Sutton & Devonport maj 523
...
http://diamondgeezer.blogspot.co.uk/2015/05/majority-2015.html?m=1