The long-running Dartmouth Square saga has taken a dramatic twist with controversial landowner announcing that he intends to build a house on the site.

The Herald can reveal that Mr Noel O'Gara intends to build a large detached home on the square, without planning permission, once Dublin City Council's 'Compulsory Purchase Order' [CPO] for the two-acre site expires on Sunday.

Last week, the Herald revealed that Dublin City Council [DCC] does not intend to proceed with the CPO obtained from An Bord Pleanala.

And now Mr O'Gara says that he may begin building works on a house, without seeking planning permission, as he believes a loophole in planning regulations means he can build a house provided he uses the park for agricultural purposes.

The Westmeath man said he wants to "show them [DCC] up as being incompetent".

The planning law in question states that "any building occupied together with land" and used for agricultural purposes is exempt from normal planning procedures.

In attempts to stop Mr O'Gara using the land, DCC have already declared Dartmouth Square as an Architectural Conservation Area and have placed preservation orders on all trees within and surrounding the square.

However, the businessman has described these as "baloney".

"The house could be built and be a nice home for a gardener and there is nothing the council could do about it," he told the Herald.

Mr O'Gara bought the two-acre site in Ranelagh in late 2005 for less than €10,000, from PJ Darley, whose ancestors built the square in the 1880s.

He previously set an asking price of €100m and sources have told the Herald that DCC are worried they could be forced to pay above €20m if they opt to enforce the CPO.

"I did put a new offer to the Council recently which is a lot less than I would be looking for under arbitration," Mr O'Gara said, but noted that DCC have not yet responded to the reduced sale amount. "It was a very attractive price but they expect it as a gift," he said.

He also hit out at Dartmouth Square residents for complaining about his use of what was once a public amenity.

- Kevin Doyle