There were unconfirmed reports that the final figure could be up to 40 million pounds (A$94.6 million), making it the biggest heist in British history.
"There is no cost at all to the Bank (of England) or the taxpayer," said a spokeswoman for the Bank of England after the robbery.
"We have already been reimbursed by Securitas for the initial estimate of 25 million and any further sum will be reimbursed to the Bank as soon as the amount is known," she said.
The manager of the Securitas main cash depot in Tonbridge in Kent was pulled over while driving on Tuesday evening by what he believed was an unmarked police car.
Police said a man wearing a high visibility jacket and a police-style hat got out of the vehicle, which had blue lights on it.
The manager, believing they were genuine police officers, got into their car, was handcuffed, threatened at gunpoint and told to cooperate or his family would be hurt.
Two other robbers disguised as police abducted his wife and son from their home, telling them the manager had been involved in an accident.
Six men, some armed with handguns, then threatened and tied up around 15 staff at the security depot.
The gang loaded the stolen money into a white lorry before driving off in the early hours of Wednesday morning.
The shocked but uninjured staff activated an alarm around an hour after the robbery. The manager, his wife and son were also unhurt.
The Bank of England said that its governor have asked for a review of the security arrangements for the storage of banknotes.
A raid at the Northern Bank's Belfast headquarters in December 2004 netted 26.5 million pounds (A$62.7 million), making it the biggest cash theft in British and Irish history at that time.