Jamie Ritblat is set to secure the control of Plantation Place, the City office building that his father built, in a £500m deal.
Mr Ritblat is reported to be in exclusive talks with Plantation Place's owners after adding to his recent takeover approach. His Delancey vehicle is backed by George Soros, the veteran hedge fund manager.
The 550,000 sq ft building is one of the City's biggest and boasts RSA, the insurance company, as one of its tenants
Sir John Ritblat built Plantation Place in 2004 when he ran British Land. His son Jamie tried to buy the building earlier this year but the deal stalled when the property's value recovered.