EVIDENCE of child abuse by the late MP Cyril Smith and other public figures was scrapped on the orders of a senior police officer as part of an establishment cover-up.

That is the allegation hanging over the Metropolitan Police today and it has momentous implications for democracy and public confidence in this country.

If the claim can be shown to be fact by an independent inquiry, it will point to corruption at the highest level.

Indeed, the questions raised by BBC Newsnight are so serious that surely no more obstacles should be placed in the way of establishing the truth. The Official Secrets Act has an important place in our constitution, but it should never be used to throw a blanket over justice.

Home Secretary Theresa May said today that she "hoped" no police officer or intelligence officer would be prosecuted under the act for giving evidence to an inquiry into the allegations. That is not good enough. The Government must be categoric in its promise that there will be no legal repercussions for those who lead independent investigators to the truth.

There is more than a whiff of scandal surrounding the activities of the former MP for Rochdale, Mr Smith – there is a worsening stench.

It is also yet another timely reminder of why we need a free press in this country. If the establishment was capable of a cover-up of this magnitude, how many other abuses of power were hidden – and how many more cover-ups might there be in future without investigative journalists shining a light into very dark places?