The message asked Trumble to come to work even as she was on maternity leave and had a difficult pregnancy. She also claimed a suspicious Mills, 42, questioned her over whether a new male pal had been flirting with her. Trumble, who quit after she was replaced as a nanny and assigned cleaning duties, is claiming undisclosed damages on grounds of discrimination over maternity leave, sex discrimination and unfair dismissal.
Mills, mum to McCartney's daughter Beatrice, six, could be seen quite disconcerted as Trumble gave evidence before a panel of three in Ashford, Kent. She shook her head and murmured "no, no" when Nick Fairweather, representing Trumble, called upon the tribunal to accept evidence Mills was a known "liar", referring to her High Court divorce ruling. However, the panel dismissed it as "not relevant" to the case.
The panel was told how Trumble met Mills in 2003 at a health club in Rye, East Sussex, where the ex-nanny was working as a beauty therapist. Mills asked if she would babysit Beatrice for her and McCartney, 67, in the evenings at their nearby home. "I thought Heather was really nice and genuine and the two of us got on very, very well," the Sun quoted Trumble, as telling the tribunal.
In April 2004 she took up the job of a nanny with Mills, who paid her 260pounds a week cash-in-hand on a self-employed basis five days a week. Trumble said: "She told me how much she trusted me with Beatrice. I thought it was a good opportunity and I fancied a change."
She went on: "I bring these proceedings with much sadness as I saw Heather as a friend. Heather can be very generous, but there was also a distrustable and unpleasant side of her. She likes to surround herself with people who will support her blindly. She is also very highly strung. I do believe that Heather is more than capable of lying and getting others to lie for her. I believe I was sidelined, perhaps as I was no more use to her."
Trumble began work at the McCartneys' home in Peasmarsh, Sussex, while Mills was still the former Beatles' wife. She said she and Mills had a "close personal relationship" and that her boss even bought her a new car - a sporty two-seat Daihatsu Copen. Mills separated from McCartney in 2006. Trumble said: "She was very bitter towards him. I was, I believe, a great source of comfort and support for her at this time."
But their relationship turned sour when Trumble returned from six months'' maternity leave after giving birth to a baby girl. She said she was asked to come to Mills'' house - while still on leave in 2007 - to record a video interview.
Trumble said: "I was asked to tell them how wonderful I thought Heather was. I felt I'd no option." Mills allegedly called her and angrily asked when she would resume her duties. Trumble said: "It was a really horrible, rude message, and it reduced me to tears."