Well, this is one that we certainly didn't see coming.

You may already have heard about Lily Allen's forthcoming 'shocking' memoir that's due for publication this year - but some juicy details of the book have just been leaked and are sure to shift an extra few copies.

According to reports, Allen is set to spill the beans on a mile high romp with Liam Gallagher that allegedly took place when both stars were on a flight to the FujiRocks festival in Japan in 2009.

The Sun reports that the Virgin Atlantic crew members on the flight 'scolded' the pair for their indecent behaviour - which allegedly took place when Gallagher was still married to All Saints star Nicole Appleton.

What's more, Allen apparently called Appleton afterwards to insist that nothing had happened between her and her husband, with a source saying: "Nicole is gobsmacked about the whole thing. At the time, Lily even called her up to insist nothing went on between her and Liam. But she’s now questioning exactly what did go on and decided to tweet her in order to ask what the truth is in a very public forum.’

The tweet in question was a rather ominous-sounding one:



Liam, meanwhile, has been suspiciously quiet throughout all of this... a publicity stunt to generate interest in the book, or a genuine story? We may never know.