By Kevin Maguire Tory rats abandoning the sinking Conservative ship is a better guide to the next general election than their two lost by-elections. Some 58 Tory MPs have already announced they are quitting next time around but the figure could top 100 – by some counts even 150. Either way, the number will easily exceed the 72 who quit in 1997, when Tony Blair took power in a landslide. So many Tories jumping before they’re pushed is a damning vote of no confidence in the Prime Minister. One Conservative former minister told me, only half-joking, he feared he’d be the sole survivor and forced …