I've actually just moved offices in London, so I can say that it actually isn't much different. There's plenty of offices that are very comparable to that price.
Ah, my mistake. Though her estimate of £1300 is still a lot more than she'd actually have to pay. My room is in a central location and costs around £670pcm with bills. It's a pretty reasonable place, it's just not 5 minutes from a tube station, which is where they'll get you on the price.