Knight Frank, the estate agent selling the Chertsey-based property, has changed its guide price to £4.5m, down from its previously advertised £5m.
Richard Griffiths, chief executive of Network Data Holdings, sent appointed representatives an update back in January saying the sale was due to complete at a price of £5m on or before March 20.
Griffiths will not confirm when the sale of mansion is expected but told Mortgage Strategy an offer for it is still there.
A number of names have been linked to the sale of the mansion, including celebrity chefs Gordon Ramsay and Jamie Oliver.
Mortgage Strategy understands an offer was made for the property in September, it is not clear whether this same offer is still on the table or another offer has since been made.