'Catherine and Diana. Two women, born twenty years apart, who never met, yet found themselves bound by a title, a ring and a man named William.'

A title in use for over 700 years, the Princess of Wales is one of the most senior positions in the British royal family. In her new book, bestselling author and pre-eminent royal commentator Ingrid Seward dives into two of the most recognisable and iconic holders of the title: Catherine and Diana.

Whilst they never got the chance to meet, both married into a family known the world over as The Firm. Two princesses, born twenty years apart, they inhabited distinct worlds - from their differing childhoods to meeting their Prince, from their approach to motherhood to defining a world-famous position, Catherine and Diana stand unique in the world.

Whilst Diana's character was both grand and vulnerable, Catherine's is more contained. Whilst Catherine's marriage is one of unity, strength and shared values, Diana faced hers alone. The late Queen described Diana as 'one of us', but it's Catherine who has been accepted in hearts and minds by all.

Through comparing and exploring their lives and loves, Ingrid tells the inside story of their relationship to the crown. With in-depth research and having interviewed Diana, Ingrid shares what defines and defined their role as Princess, and just what kind of personality from outside the family ends up on the inside.