Hindmarch, who passed away on 27 August, set up EHPR in Windsor in 1982.
Representing clients including Miele and P&G owned Wella Professionals, she built a business that eventually employed more than 30 staff when it was sold to Huntsworth in late 2002.
The EHPR brand disappeared when it merged into fellow Huntsworth agency Trimedia in 2009. Staff who worked for the company over the years have gone on to senior positions across the industry.
Her former colleague Alison Clarke, who worked both for Huntsworth and as UK CEO of Grayling, said: "Elizabeth was a consummate professional, a perfectionist and highly regarded by clients and colleagues alike."
The funeral will be on 14 September at St Andrew’s Church, Sonning, at 11am. Donations can be made in her memory to the Royal Marsden Cancer Charity, care of funeral directors AB Walker. Family flowers only.