There was a 'non aggression pact' in place a couple of years ago which resulted in scandals like this one being given vary little publicity. As Peter Oborne wrote about the 2003 inter party deal:
The origins of the sordid little deal go back to the summer of 2001, when
Labour business managers decided on the assassination of Elizabeth Filkin.
Filkin's crime was to take her job - parliamentary commissioner for
standards - seriously. When evidence of wrongdoing came her way, she
investigated. A number of Tory MPs - Teresa Gorman, John Major and William
Hague among them - were embarrassed by her inquiries. So were Cabinet
ministers like John Reid, Peter Mandelson and John Prescott. In many cases
her findings were so incendiary that the Labour-controlled standards and
privileges committee watered down her findings. Martin Bell, the
sleaze-busting MP who sat on this committee, has since claimed that the
Labour whips office applied improper pressure to ensure helpful results. A
striking number of its relatively obscure Labour members were given peerages
after the last election. Perhaps that is simply a coincidence.