Ms Holland, a pensioner from Birchanger, Essex, remains in critical condition in hospital.
In a statement released to Sky News on Saturday, her family described her as a “beautiful, loving, kind and caring lady who would always put anyone before herself”.
“The family are deeply saddened and shocked at the news Helen was involved in such a tragic accident," they said.
“Helen may be 81-years-old but she is sprightly for her age and nothing stopped her living life to the full, spending precious time with her family, muddy walks with the dogs and lunches with friends is what she enjoyed most."
The family added: “This been a huge shock for many. The outpour of love and support the family have received from those that know her is hugely appreciated.
“We are all praying for a miracle and ask that you keep her in your thoughts and prayers too.”
On Thursday, Buckingham Palace said in a statement Sophie is “grateful for the swift response by the emergency services”, adding that she will “keep abreast of developments”.
A statement added: “The Duchess’s heartfelt thoughts and prayers are with the injured lady and her family.
“She is grateful for the swift response by the emergency services and will keep abreast of developments. Further comment at this time would not be appropriate while the incident is being investigated.”
Images from the scene showed a bike used by the Metropolitan Police special escort - which protects royals and top politicians - inside a cordon.
Scattered nearby were a single trainer, a brown paper bag, a face mask and a bottle of hand sanitiser.
The Met said an investigation into the crash is ongoing and road closures remain in place.
The force’s directorate of professional standards and the Independent Office for Police Conduct have been informed, which is usual following an incident involving an officer.