But it is investigative journalism

There is a fair amount of controversy about the story which broke in the Mail on Sunday about the Mirror investigative journalist Emily Miller who tried to infiltrate
Tory party Hq.As the Mail reports

Emily Miller, 25, who claimed to work for a charity that helps Indian children, applied for a £40,000-a-year job as assistant to Conservative Party chairman Caroline Spelman.
She said she wanted to help Mr Cameron to defeat Gordon Brown at the next Election. But her real aim was to spy on the Conservatives' Election plans and to help Labour win a fourth term.
Ms Miller was caught out when the Tories discovered her Hotmail email account was linked to the Daily Mirror, Labour's main cheerleader in Fleet Street.

There have been calls for legal action and the PCC to get involved.But am I missing the point.This is investigative journalism,it is no different surely to similar cases of infiltration and dont the public have a right to know what is going on behind the close doors of our political parties?