Firstly, adjust that Babelfish for Fabianese. It is important to note words like 'progressive' and 'radical' have meanings significantly different than their counterparts in standard, freeborn English. With all such value words, it is useful to assume the antonym is intended.
This is clear in the party's name, where 'Liberal' has come to include a belief in a benevolent, hegelian state -an oxymoron if ever there was one.
And whatever 'democrat' means must be discerned with reference to the party's foul betrayal of its manifesto commitment to support a referendum on the last EU treaty.
Anyway, turning to Polly, we find:
"If he [Nick Cleg] was serious, he could go for Labour's jugular with an unequivocally radical message. The empty political ground is not in the crowded centre, but out in the near-deserted radical wastelands. But Clegg looks over his shoulder, anxiously protecting those essentially conservative seats that so many of his MPs hold."
Polly offers no real clue as to what she means by 'radical', although she mentions the party's opposition to the Iraq war and tuition fees as possible moments of radicalism, and when she concludes she seems to contrast 'slash and burn' cuts with being radical.
But what of the 'near-deserted radical wastelands'? I would say those wastelands are far from deserted, indeed they're not even wastelands. That's where you find all the rest of us who can't stand the Lib-Lab-Con brigade, all the ideas that that lot doesn't dare to even contemplate out loud, in other words the majority of the people. Out in the wasteland, we're not a bunch of savages waiting for the missionary man to proselytise us back to the centre ground, we're organising. We're trying to think up a way, not to return to the centre ground, but to march on it, besiege it, smash it to smithereens.