Duncan Wilson, the agency’s chief executive, said this week that there has been "a slow decline" in council conservation staff since 2006 and that "we may start to feel the effects soon".
Wilson was speaking at the launch of results from a poll on public attitudes towards conservation areas, 50 years after Stamford in Lincolnshire became the first such area to be designated.
The YouGov poll found that the top two issues deemed to be negatively affecting the appearance of a place are the same for those living in and outside of conservation areas - too many parked cars (43 per cent for both groups) and litter and fly-tipping (38 per cent for those in conservation areas and 41 per cent for those outside).
Historic England said it is revising guidance to help council staff combat such issues.
The poll also found that people who live in a conservation area are almost twice as likely as the general population to have lodged an objection to a development or a planning application (24 per cent compared with 13 per cent).
But only a small majority of those surveyed who live in a conservation area - 56 per cent - were aware that they actually live in one. Historic England said this suggests a need to raise awareness.
Wilson said the poll showed that conservation area legislation is "still relevant 50 years on from when it was introduced" and "a tool that local authorities have in their armoury to protect the local historic environment, which is precious to people and communities".
"Without this legislation, historic buildings, streets and landscapes would have been lost forever," said Wilson.
"Conservation areas must be protected - they have an important role as we look to the future and can help councils, civic groups and communities to preserve what’s really special for future generations to enjoy."