Heath Ledger was "intense" and totally absorbed in the making of new fantasy film The Imaginarium of Dr Parnassus - which he died half way through filming.
That's according to singer and actress Paloma Faith, who co-starred with Heath in the movie.
Paloma - who's being touted as the new Amy Winehouse - made the revelation on Fearne Cotton's new BBC Radio1 afternoon show.
She said of the star: "He was intense and worked really hard, he was really involved in the whole process".
Paloma also co-starred with Girls Aloud blonde bombshell Sarah Harding in the latest St Trinian's movie, but told Fearne she hadn't got to know her at all as her security guards kept everyone at bay.
More recently however, Paloma has filmed a guest appearance on Never Mind The Buzzcocks - and she revealed that Noel Fielding was chasing her for a date.