Watch BBC's The Diamond Queen Episode 2

In the second of three programmes, he assesses her moves to modernise the monarchy, from the abolition of the presentation of debutantes in 1958 to the very modern wedding of William and Catherine last year. Princes William and Harry are on hand to talk about their grandmother's influence on the wedding day, from the guest list to the choice of uniforms. Andrew also looks back at the challenges faced by the monarchy in the 'annus horribilis' of 1992, follows the Queen on her groundbreaking visit to the Republic of Ireland last May, and looks back on the happy times she spent on the Royal Yacht Britannia and the sadness she so visibly exhibited when it was decommissioned in 1997. Peter and Zara Phillips talk about family holidays on the yacht and Tony Blair speaks of the difficult decision he took to scrap it when he came to power in 1997.

Producer: Sally Norris
Presenter: Andrew Marr
Director: Sally Norris
Executive Producer: Nick Vaughan-Barratt