Mr Montague faces a bankruptcy hearing at the end of this week in Oxford County Court. He is said to have amassed personal debts of more than pounds 40m.
The value of country estates rose astronomically during the 1980s, but the price falls during the recession were at the forefront of the property slump.
Mr Montague bought the estate from Sir Simon Hornby, chairman of WH Smith, in 1990 - the year when the downturn in property prices started to accelerate sharply.
Barclays Bank has an pounds 8m mortgage secured against the estate, but it is not yet clear whether it will back the move being made to bankrupt Mr Montague by Royal Bank of Scotland, which is owed some pounds 2.3m, or whether it will support Mr Montague's attempts to avoid bankruptcy by having his creditors agree to an individual voluntary arrangement.
Mr Montague's other debts include one of pounds 7m to Commerzbank, the German bank, on a 139ft yacht. Worldwide prices of luxury yachts have also been ravaged by the recession. More than half the Montague family's debts are with Commerzbank. RBS could face a tough fight against Commerzbank to have its bankruptcy order passed by the courts.