Whilst at London First, Lady Valentine was instrumental in the creation of Teach First, campaigning for Crossrail and the Olympics and championing the development of the South Bank of the Thames.
Prior to London First, Lady Valentine worked in corporate finance at Barings Bank, where she became the first female manager.
In 1990 she joined The BOC Group to head the corporate finance and planning function, leaving in 1995 to establish the Central London Partnership (CLP).
She has held many non-executive roles including Peabody Housing Association, HS2, Crossrail, and was on the National Lottery Commission.
She was recommended by the House of Lords Appointments Commission to be created a life peer, taking the title Baroness Valentine, of Putney in the London Borough of Wandsworth on 10 October 2005.