The Civic Trust which has co-ordinated civic societies across England and campaigned for urban protection and regeneration since 1959 has closed due to lack of funding.
The Trust has long been a voice for local people in urban planning and regeneration but it has been an increasingly silent voice in recent times as the funding crisis hit NGOs.
It blamed its demise on the squeeze on local authority spending.
The other civic trusts - the Scottish Civic Trust, the Civic Trust for Wales and the North of England Civic Trust - all expressed regrets but said their work will continue as normal.
"I still passionately believe in the civic movement, but it now needs grassroots members of vision and energy to start afresh with a new organisation, working within its means and building gradually from the bottom," said Trust chairman Philip Kolvin QC.
North of England Civic Trust director Graham Bell said the news would not affect his own organisation's work.
Town & Country Planning Association chief executive Gideon Amos said the standards that 50 years work by the Trust had taught us to expect from development should not be thrown out.
