In London, Palmer's Lodge was an amazing hostel. It is not really central (it's a bit north, the nearest Tube stops are Swiss Cottage and Finchley Road) but the Tube is so convenient that it never takes more than 20 minutes to get anywhere. The area is beautiful - near Abbey Road Studios, if you are a Beatles fan! - and there are restaurants and a huge grocery store really close by. I LOVED this hostel, the 14 bed dorms are only 15 GBP a night, and that includes free sheets, free breakfast, and free internet and Wi-Fi. It is very clean and comfortable too - definitely recommended!