She became the United Kingdom's first female newsreader after she was recruited to present the Midday News on the newly launched Independent Television in 1955.
Mandell was born in London, England, daughter of Royal Navy Lieutenant-Commander Yvo Hedworth Fortescue Grenville Wells, later deputy editor of The Rand Daily Mail,[1] and Clara Isabella, daughter of Henry Wheaton, of The Abbey, Cambridge.
The Wells family were shipbuilders who rose to the rank of landed gentry, owning Bickley Hall, Kent and Holmewood, Huntingdonshire until selling them during the nineteenth century.
Her father was the deputy editor of South Africa's Rand Daily Mail and Mandell followed him into journalism, working for the same newspaper.
After working for the BBC's Television Newsreel as a script editor she joined ITV upon its launch in 1955, and was one of three people chosen to present its news bulletins.