British journalism is generally much happier to rely on single anonymous sources to break news, and I think you really see the problem with that in Brexit coverage.
These stories have a really poor track record of turning out to be either meretricious smears or just false bluster.
Either way, the source or sources have a terrible track record and should be treated with extreme caution.
At the very least people shouldn't be running stuff from these sources, even on Twitter, without *verifying* with other sources with better track records.
But *getting things right* should be the priority.
I'd suggest that a powerful and well-connected figure with a track record of lying to the media is an *extremely bad source*.
That's the step that appears to be getting missed at the moment.