Politicians and journalists are often thought to form twin élites or even a single, overlapping élite. And today's revelations by two former Downing Street insiders - Damian McBride and Benjamin Wegg-Prosser - certainly give credence to that belief.

Their struggles on behalf of their masters - Gordon Brown and Tony Blair respectively - are all about influencing journalists in order to manage the news agenda.

For their part, journalists and editors appear eager to oblige, sometimes out of political loyalty or, more usually, accepting that publishing single-sourced leaks (aka briefings) is the price to pay for obtaining headline-winning "stories"

There are occasions when it is difficult to tell between the two. For example, one of Wegg-Prosser's emails refers to a call by Roger Alton, the then editor of The Observer, in which he says it is now clear to him that Brown should not become prime minister.

The message continues: "Wants to know how to help this weekend."

That "help" is revealed the next day when Wegg-Prosser emails Blair's chief of staff, Jonathan Powell, to say The Observer "are trying to do a poll which shows how bonkers GB is."

Wegg-Prosser adds: "Do you think we could set up another TB - Roger [Alton] call this weekend. It is crucial to keep them onside."

Two days later, The Observer's front page headlines reads "Cabinet turns on Brown in hunt for alternative PM".

In McBride's book he tells of newspapers publishing tales he has leaked to them. One instance involved John Reid, who subsequently resigned as home secretary.

McBride claims that, following the publication of his leak, a journalist friendly with Reid and his special advertiser, Steve Bates, called to discuss the "news", saying: "So you can call off the dogs now." McBride continues:

"I asked what he meant. 'You know what I mean; there's no need to go for him now.'"

In other words, that journalist, and others, were aware of the dirty tricks and the identity of the dirty tricksters. But that important knowledge remained confidential, known only to those "in the beltway."

The same was evidently true of his planted tall tales about other ministers, such as Charles Clarke and the then junior health minister Ivan Lewis.

He tells of his determination to treat Lewis to "an iron fist in the face" because the MP had the temerity to question his bullying tactics.

The result? A News of the World splash about Lewis's alleged pestering of a young civil servant who used to work in his private office.

The trade in information and gossip (and falsehood) between journalists and politicians (and those acting for them, such as press aides and special advisers) has become a matter of custom and practice.

It provides a steady diet of copy for newspapers, with consequent TV and radio interviews. But what does it provide for the people?

Should we journalists not worry about whether we are genuinely serving the public interest? By taking part in this charade, surely we not holding power to account.

Sources: Benjamin Wegg-Prosser's emails are published in The Guardian here. See also here

Power trip: a decade of policy, plots and spin, by Damian McBride (Biteback Publishing) is being serialised in the Daily Mail here and here. See also here