PJ Harvey, Royal Festival Hall

"Ooh, no drum kit!" says someone behind me. They're right, too. It must be a small band Polly's got with her tonight.

No it isn't. It's no band at all. PJ Harvey slides onstage in a Victorian frock (as seen of the cover of her new album) and proceeds to play for an hour an a half all on her own. She's got an array of instruments - guitar, piano, autoharp, synths, drum machines - and a couple of roadies who bring them on and off ("Aren't they lovely boys?" she grins). Otherwise, it's just her. There aren't many people who could do this, but her songs actually become more impressive in this spartan setting, somehow seeming even rich and more complex than they do in their recorded incarnations. And of course the most extraordinary instrument of the evening, her voice, ranging from bluesy growl to angelic shimmer, with everything in between.

She's in a fine mood, pottering about the stage from instrument to instrument like a dotty aunt, chatting to us as though we were watching her in the back room of a pub rather than the Royal Festival Hall. In this setting, songs which we always thought of as blues based turn out to sit very nicely in the English folk tradition, and the new songs turn out to be a perfectly natural enriching of what she's already achieved. She plays guitar, and without a band around it, we're reminded just how good she is at that. She plays piano, and seems a bit nervous about that (she doesn't need to be). She plays synths, and does that slightly weird dancing she does, that looks even more singular in that dress. She swears at a drum machine that won't work, then shrugs, noting with a grin that "sometimes you have to accept that when you turn these things on they just don't work... like a lot of people, I guess." Then she plays the songs without the drum machine, and it's mesmerising anyhow.

At the end she gets a standing ovation. "Thank you for coming, and thank you for supporting me!" she says. She means it. She's clearly enjoyed herself, and so have we.

It wasn't at all what I expected. It was an hour and a half long. there was no support. The tickets cost 40 quid. It was one of the best gigs I can remember going to, worth every penny. Polly's a genius.

White Chalk

Honestly, you wait ages for a decent record then two turn up at once.

Hot on the heels of Joni Mitchell comes Polly Harvey with her latest album, White Chalk. And like Mitchell, Harvey is someone determined not to rest on her laurels. This album finds her abandoning her guitar for piano and an array of string instruments (by which I mean zithers and autoharps rather than violins), as well as abandoning her growly, bluesy voice for a much higher, purer tone, almost like a choirboy.

This is the sort of sound that chimes very well with all sorts of things I've been thinking of lately, so it may be that I'm feeling particularly receptive, but this album's absolutely brilliant. To step so far out of one's comfort zone is an achievement in itself, to do it with such aplomb and success is astonishing. It's also strangely uplifting, in a macabre sort of way. I've loved Polly's music for a very long time, and my admiration for her has grown pretty consistently with each new release, but it's rocketed with this one. To be able to come to this from "Rid of Me" all those years ago puts her into the same league as Joni.

Two wonderful albums from two fantastic musicians in one week is a rare treat. Just to reassure you that the world hasn't suddenly started making sense, there's a new Westlife album on the way. Can't win 'em all.