I'm a Londoner, I used to have this friend (who is not a Londoner) we had a huge disagreement on topic unspecified. But after I've watched this video I think I see his viewpoint, which is true. I just don't see it at all because there's such a enormous disconnect between London and the rest of the country.
I would recommend you to watch the video as well, some arguments made in the video are slightly misleading, but the general picture is clear and true.
I'm sorry but if you recommend an hour long video to start a debate you're not going to have much success...
because I have never heard of this argument before, ever. most media's stance on politics is "their party bad our party good", but the "all the parties are pretty hypocritical" argument has never been explored properly, because its depressing and nobody likes it.