Born in 1967, into a family with a long Royal Naval tradition. During her childhood and early teens the Campbells moved home 24 times — which resulted in Ffyona attending 15 schools.

After leaving home and school at 16, she raised the necessary sponsorship to enable her to walk from John o' Groats to Lands End. Walking 20 to 25 miles a day 6 days a week, she completed the journey in 49 days and was the youngest person at that time to have done it. Through sponsorship from The London Evening Standard, she raised 25,000 for the Royal Marsden Cancer Hospital.

At 18, she set off from New York crossing the United States towards Los Angeles. The relationship with her support crew was volatile, and the schedule to coincide with the sponsors' public relations events en route was demanding. Due to illness, she couldn't keep up the schedule but didn't want to let anyone down and so broke her own golden rule and accepted a lift from her back-up driver to catch up. This happened over a distance of 1,000 miles until she was well again. It was a highly traumatic experience for an 18 year old and she never spoke of it at that time.

At 21 she walked across Australia, 50 miles a day for 3,200 miles from Sydney to Perth in 95 days, beating the men's record for this journey. She suffered severe blistering of the feet but was determined not to miss out any miles. She wrote about this journey in her book Feet of Clay.

On 2 April 1991, she left Cape Town, South Africa and walked the length of Africa covering over 16,000 km (10,000 miles) before arriving in Tangiers, Morocco two years later on 1 September 1993. She had been joined by her ex-boyfriend, British survival expert Ray Mears, for five months during the journey through Zaire after an uprising had forced her and her team to abandon the support vehicle and be evactuated by the French Foreign Legion along with all the other ex-pats. The walk raised awareness of Survival International, the organisation which helps protect the lives of threatened tribal people. She wrote about this journey in her book On Foot Through Africa.

In April 1994, she left Algeciras, Spain and walked through Europe, arriving in Britain at Dover. She then completed the last 1,300 km (800 miles) walking from Dover back to John o' Groats supporting Raleigh International, arriving on 14 October 1994. She was shadowed by a BBC film crew and presenter Janet Street-Porter.

Campbell raised half the amount for charity in one go by selling the advertising space on her forehead during her well-publicised return. After a period in hositpial for a back opertation, she went back and walked across America again for her own personal satisfaction and wrote about that journey in her final book, The Whole Story. The media castigated her for it. New Statesman - Gone, and (almost) completely forgotten