Woman Linked to David Harbour Asked to Leave Lily Allen Producer's Party

Morgan Cozzi -- who was linked to Lily Allen's ex-husband, David Harbour, late last year -- was asked to leave a birthday bash for Lily's longtime producer ... TMZ has learned.

Sources with direct knowledge tell TMZ ... Cozzi showed up February 20 to a party for producer Blue May at his home in Los Angeles' Beachwood Canyon -- the very same house where Lily wrote and recorded her latest album "West End Girl."

We're told Lily wasn't at the party -- she was in London -- but plenty of her close friends and collaborators were in attendance. Rita Ora was also there, as she was currently working on her album with May. According to our sources, Cozzi arrived as a "friend of a friend," and at first, her presence didn't raise any red flags.

But once guests realized Cozzi had been linked to David, the vibe shifted ... and we're told she and the friends with her were asked to leave by a security guard working the party.

As you know ... David and Lily split early last year, before she later alleged in her album "West End Girl" that he had cheated during their marriage.