Lily Allen gave birth to a baby girl five weeks ago, and she's done a good job keeping her daughter's name a secret -- until now. Allen's mother, an obviously doting grandmother, recently let the name slip via Facebook!

Allen's mom, Allison, shared the news of baby Ethel Mary's arrival with all of her social media friends, despite her daughter's attempts to keep the details of the birth under lock and key. We're sure Lily doesn't blame grandma, however, as she is likely just gushing over the new bundle of baby joy!

Ethel Mary, or 'mini Cooper' as we knew her before, made her entrance on Nov. 25 and was an especially welcome gift for Lily, who has suffered multiple miscarriages in the past. Just last year, she and her husband Sam Cooper were saddened by the loss of their unborn son, who was six months along. We're sure that the whole Cooper-Allen gang is relieved that they've entered 2012 with a healthy baby girl.