Chairwoman Baroness Andrews said: "These have been testing times and we have to tell the bigger story to win the case for heritage as a national asset.
"It's clear to me it has proved difficult to get the attention of successive Governments about what we are doing," she told a national conference last week.
Andrews said the response to the budget cuts was not to "batten down the hatches" but win the case for why heritage mattered so much to the country.
"We need to say why it is part of the solution to the challenges we face," she told members of the Historic Houses Association in Westminster. "We need to be less diffident about the social and cultural benefits. It's not just about X number of visits or a Y decrease in crime. A sense of place is critical to society and heritage conveys pride in our communities."
Andrews said English Heritage was to reduce its grants programme by one-third following a 32 per cent budget cut - against a cut of only 15 per cent for museums.
Job losses would hit all levels, from senior managers to expert and administrative staff. However, it would continue its planning advice to local authorities.
She said a heritage protection fund would enable English Heritage to prioritise gardens, buildings and townscapes most at risk in a "transparent and systematic way".
Historic Houses Association president Edward Harley urged prime minister David Cameron not to ignore the importance of historic gardens and houses to tourism and regeneration.
"Cameron said heritage was a key reason why people came to Britain and we should play it up. But we want actions not just words, against cuts of up to 34 per cent."
The Marquess of Cholmondeley, owner of Houghton Hall and Gardens in Norfolk, said his restored garden drew as many visitors as the home and return visitors often went back because of the garden.