Actually, "rumours" is part of the problem here. It's not rumours, since there are news items about people willing to back Blair etc. How about :

increasingly detailed news items have made evident a wish...

(Though "instanced" is not a good choice, I don't think there's an "upper-class/lower-class" issue here. The language of a petition should be as exact as possible, that's all. If you deliberately write it in tabloidese, the kind of people who sign petitions will take no notice of it - sorry if that sounds snobbish, but it's a fact).