Wallis Simpson, the woman for whom Edward VIII abdicated the throne, may still have been in love with her husband, unseen letters have shown.

The American divorcee, who became the Duchess of Windsor, was also lonely and felt trapped into marrying the king, according to a new Channel 4 programme which examines 15 of her private notes.

Anne Sebba, Mrs Simpson’s latest biographer, said she was out of her depth and perhaps still in love with her second husband Ernest Simpson, the Radio Times revealed.

The British monarchy was rocked to the core by the constitutional crisis when the king turned his back on the crown, choosing love over his royal duty in December 1936.

But Mrs Simpson struggled with the events herself. Most of the newly discovered letters were to Ernest, whom she was in the process of divorcing.

“None of this mess and awakening emptiness is my doing,” she wrote.

In another letter, she proclaimed: “I miss you and worry about you. Wasn’t life lovely, sweet and simple?”

This year marks the 75th anniversary of the abdication.

Sebba said: “As an American, (Mrs Simpson) loved the access to the highest levels of English society, to be showered with blandishments and expensive jewellery, to be the mistress of the future king.

“But she expected the eventual fate of most mistresses, which is to be dumped.”

Edward and Mrs Simpson married in June 1937 following her divorce from Ernest. They spent most of the rest of their lives in exile in France.