She will now concentrate on helping just six: the Centrepoint charity, which provides shelter for the homeless, the English National Ballet, the Leprosy Mission, linked with Mother Teresa, the National Aids Trust, Great Ormond Street Hospital for Sick Children, and the Royal Marsden Hospital in London, which specialises in cancer research and treatment.
Many of the other charities said last night that they would find it difficult to attract financial support without the Princess as a patron and star attraction. The charities she has dropped include the British Red Cross, Help the Aged, the Parkinson's Disease Society, Barnardos, and Relate.
Jane Atkinson, spokeswoman for the Princess, said the decision was made "with regret". It is understood she wanted her former charities to be free to seek another royal patron, now she is technically no longer a member of the Royal Family.
Although letters were sent out to the charities on Monday, some did not know of the decision when the announcement was made yesterday. They reacted with surprise at the news, which came only months after the Princess expressed a desire to be a "Queen of hearts" in her Panorama interview.
Charity consultant Fiona Fountain said the Princess' resignation is likely to cost charities thousands of pounds: "You can increase the price of a ticket so much more if you have got the Princess of Wales attending - it can add at least pounds 50 to a ball ticket. That adds up." She said that the loss was more likely to be felt by larger charities able to stage the kind of functions the Princess would attend.
John Mayo, director of Help the Aged, said their income had quadrupled under the Princess' patronage and they were "greatly saddened" to lose her. "The Princess of Wales has brought light and hope to the lives of thousands of older people both at home and abroad."
Diane Yeo, chief executive of the Malcolm Sargent Cancer Fund for Children, said she was sorry the Princess had resigned.. A spokesperson for Relate, the marriage guidance organisation, said: "We are grateful for her past patronage and would like to offer her every good wish for the future."
Roger Singleton, senior director of Barnardos expressed his "great regret" at losing the presidency of the Princess of Wales and the weight she lent to the charity's work with children. At least one charity, the Ty Hafan Children's Hospice in South Wales which is not yet built, plans to ask her to change her mind.
Derek Bodell, director of the National Aids Trust, one of the charities the Princess will continue to work with, said they were thrilled: "We believe she has done more than almost anyone else to combat the stigma and misconceptions that still surround HIV and Aids. We are delighted and feel privileged that the Princess of Wales has announced her continued patronage of the trust."