The Sun says that the Hampstead property, which is owned by developer Matthew Frayne, is back on the market. Frayne has apparently turned the contestants' music room into a children's play area, while the acts' dressing room is now a study.
Frayne took the home off the market in 2009 when he was approached by X Factor producers Talkback Thames about using the building.
Speaking about the house last year, Frayne told The Daily Telegraph: "It's a niche house - we didn't expect it to sell immediately. It's very sharp and contemporary. We were considering lowering the price but now houses are shifting again we feel more positive. You're getting a lot for your money."
The property has six en-suite bedrooms, a sitting room, an open-plan kitchen/breakfast room and a media area.