DUP leader Ian Paisley tried to persuade Moyle Council to back away from an alternative to tycoon Seymour Sweeney's centre proposal for the Giant's Causeway, it has been learned.
The intervention by Dr Paisley in 2005 could have scuppered the development of plans for a new publicly-funded visitor centre at the north coast attraction.
Moyle Council rejected his plea at that stage, but has recently seen the project shelved as a result of actions by DUP Ministers.
The council entered into a partnership in 2005 to deliver a replacement for the Causeway centre that had burned down five years earlier.
This scheme also involved the National Trust, Northern Ireland Tourist Board and the Department of Enterprise.
Mr Paisley, however, preferred an alternative commercial centre blueprint tabled by developer Seymour Sweeney, who is a DUP member.
In early 2005, the DUP leader issued a statement with his politician son Ian Paisley Jnr denouncing the Government-backed project as "fool's gold" .
It has now been discovered that Mr Paisley followed this up with a last-ditch appeal to Moyle Council in September of the same year.
He wrote to the council on the day that it was due to formally sign up to the joint project, urging it not to take a decision at that time.
A copy of the letter, which was faxed from Mr Paisley's office, has been obtained by this newspaper.
It claimed that "hasty action" would damage ratepayers' interests and decisions should not be taken "without exploring all of the commercial, legal and professional options available".
And it added: "Taking a binding decision without first exploring all of the options would be negligence and I know that Moyle Council has a record of ensuring that it considers such matters appropriately."
The council, nevertheless, voted that day to sign up to a joint Causeway centre company with its partners.
Minutes from the meeting indicate some annoyance within the council at the DUP leader's letter.
The plans to develop a publicly-owned visitor centre could not have been taken forward without Moyle Council's involvement, given its ownership of existing buildings and the Causeway car park.
The council-backed scheme was shelved last month by DUP Minister Nigel Dodds, after DUP Environment Minister Arlene Foster announced that she was " of a mind" to approve Mr Sweeney's rival project.
Both Mr Dodds and Mrs Foster have denied being approached by their party leader or Ian Paisley Jnr on the matter.
This newspaper revealed last week that Dr Paisley had claimed in a 2003 letter that Mr Sweeney's plans had the approval of international body UNESCO.
The organisation, which oversees world heritage sites like the Giant's Causeway, categorically denied giving any such backing.
SDLP MLA John Dallat yesterday announced that he is referring the 2003 letter to the parliamentary standards watchdog in Westminster. Mr Paisley Jnr has claimed the letter's references to UNESCO approval were "fair" .
Moyle Sinn Fein councillor Cara McShane yesterday commented: "The letter in 2005 to our council raises yet more questions in this whole affair.
"It is strange that Mr Paisley was urging people not to take decisions in 2005, five years after the old centre had burned down. In recent weeks, his party has been hitting out at the delay in getting a new centre."