There is an offence of Contempt of Parliament which is defined as (Also see here):
Any action taken by either a Member of Parliament or a stranger which obstructs or impedes either Parliament in the performance of its functions, or its Members or staff in the performance of their duties, is a contempt of Parliament. Examples of contempt include giving false evidence to a parliamentary committee, threatening a Member of Parliament, forgery of documents and attempting to bribe members.Clearly as getting leaks and using them to hold government to account are part of parliaments daily business then interfering with that is contempt of parliament.
The police officers involved need to be arrested and brought before parliament.
The speaker, Michael Martin also needs to be relieved of his position as he has clearly failed to protect parliament.
Labour bloggers are apparently talking all sorts of twaddle on the subject. Consider this from Daniel Finkelstein on what was leaked to Gordon Brown when he was in opposition and ask yourself the question; would you want that stifled? Would that be in the interests of democracy?
Iain Dale also has this, Dizzy has this and Guido has this. The Guardian also has this.