The meeting, organised by TATAS (Trevalga and Trethevy Against Sewage), was due to take place on Wednesday night at Trevalga Village Hall.
Glenton Brown, the Cornwall County Councillor for the Tintagel Electoral Division, had agreed to attend and take part in a question and answer session on the application by South West Water to install a sewage treatment works at Trevalga.
Around 40 to 50 people were due to attend the meeting, but Cllr Brown pulled out on Monday evening.
Cllr Brown told Mr Clive Baylay, chair of TATAS (Trevalga and Trethevy Against Sewage) that he had been advised against attending a protest meeting by the new Chief of Planning.
When Mr Baylay suggested changing the format of the meeting to a parish meeting, Cllr Brown also refused to attend that.
Mr Baylay said he spent four hours on Monday evening phoning people to inform them that the meeting had been cancelled.
As well as members of the public, members of CLASP (Concerned Locals Against Sewage Proposals) were due to attend the meeting, along with members of Tintagel and Forrabury and Minster Parish Councils.
"All in all, various people had rearranged their lives to be there. It's caused a great deal of inconvenience to people. They are very angry about it."
Mr Baylay said a lot of time had been spent on the agenda for the meeting and the format of the evening, and added: "We had a lot of very important questions to put to Mr Brown. Other people had spent time on their questions they were going to ask. I really wanted to challenge him on a lot of things. Our parish is now without representation."
Cllr Brown told the 'Post': "The advice I was given was that I shouldn't be involved in pro or anti meetings prior to a decision coming up at full planning."
The application was deferred at a recent Cornwall County Council Plans Committee meeting, and is due for consideration at the next planning meeting on February 19.