Property developer Noel Smyth has agreed to pay €320 million for Quinlan Private's major stake in the Square shopping centre in Tallaght, Co Dublin.

Contracts on the sale were finalised yesterday after Mr Smyth saw off competing bids from fellow developers, Liam Carroll and Treasury Holdings.

The deal will see the transfer of a portfolio of 68 shops that Quinlan Private has been building up since 1991.

Mr Smyth, who already owns 18 shops in the centre through his Alburn company, will now take control of about half of the development. The remaining stakeholders are AIB Investment Managers and Alanis, a company controlled by the McCormack family.

Mr Smyth said last night that the Square had suffered in the past from having "too many owners".

He believes the three owners now in place will be well placed to bring the Square back to its original status as a landmark centre.

At present, the shopping centre attracts 19 million visitors a year.

It stands on seven acres but has space to expand on to a further 20 acres.

Mr Smyth is already planning a €500 million redevelopment of car parks at the Square which he is acquiring from South Dublin County Council.

Over the coming two years, this will involve the construction of offices, hotels and more than 300 apartments, as well as new outlets for retailers such as Penneys and TK Maxx.

Quinlan, which has been better-known in the past few years for buying assets than selling them, was one of the original investors in the Square in 1991.

More recently, the firm has focused on building its stake to a "critical mass" level, according to Thomas Dowd, the Quinlan partner who concluded the deal with Mr Smyth.

The sale will deliver substantial returns for the investors who have joined Quinlan in the Square investment over the past decade and a half.

The sale price suggests a twenty-fold return on money invested in the project at the start of the Square's life, when it was viewed as one of the most impressive retail projects in Europe.

Quinlan Private itself will also draw a return from the deal, with the investment group typically taking 10 per cent of the equity in assets it purchases.

Any outstanding borrowings relating to the Square are likely to be small relative to yesterday's sale price.

Given that Quinlan invested in the Square at an early stage in the investment group's existence, it is thought the individual investors involved could number as few as 25.

The 68 shops being sold carry a rent roll of about €10 million, implying a yield of 2.8 per cent.

This does not take account of the potential for redevelopment or new rental agreements.

Quinlan is thought to have a pipeline of other assets that are for sale, while also considering a large number of potential purchases.

"Selling well is as important as buying well," said Mr Dowd.