Dunne has agreed a swap with Irish Life's Irish Property Fund under which he will acquire the 80,000 sq ft Hume House on 0.9 acres in Ballsbridge at a price understood to be 130m.

This latest acquisition brings to about 57m an acre the average price of the land Dunne has accumulated in the Ballsbridge site bounded by Shelbourne Road, Lansdowne Road and Pembroke Road. He paid 66m an acre for the seven-acre Berkeley Court and Jurys Doyle site.

Dunne's total eight-acre Ballsbridge site now includes 200 metres of frontage on Pembroke Road. Glenkerrin Homes' Grehan paid 171.5m for the adjoining former Veterinary College on two acres. It is understood that Dunne and Grehan may team up to apply by the end of this year for permission to develop the sites.

Dunne's acquisition of Hume House means the entire island of Ballsbridge land currently housing the hotels is now controlled by developers. Bernard McNamara and Joe O'Reilly jointly bought the 0.3-acre Office of Public Works site there for 36.5m, while the O'Malleys of Galway-based O'Malley Construction bought Shelbourne House, behind the Berkeley Court, from the Doyle sisters . . . daughters of the late hotelier PV Doyle . . . in 1999.

In exchange for Hume House, Irish Life gets the 133,000 sq ft Block A in the Riverside IV development that Dunne is building in the Grand Canal Docks area beside the Liffey. It is understood that Irish Life will also pay Dunne up to 40m in cash by the end of next January, depending on certain conditions being met. This values the Riverside A block at 170m.

Law firm Matheson Ormsby Prentice will lease the Riverside A building for 25 years, with an option to extend for a further 10 years.

Dunne is building a total of of 270,000 sq ft of office space in three blocks in the Riverside development, and it is understood that Matheson Ormsby Prentice has also taken an option on over 65,000 sq ft, or four floors, in Riverside Block B, which can be exercised over six years.

The law firm, which currently employs 550 people, will pay 52 per sq ft for the office space. It is due to move into Riverside Block A in January next, with Dunne taking over the lease on the firm's current 50,000 sq ft headquarters in Herbert Street, owned by Treasury Holdings' Johnny Ronan.