Here's a major laugh for a long holiday weekend in the US: Secret Bank of England taskforce investigates financial fallout of Brexit

Bank of England officials are secretly researching the financial shocks that could hit Britain if there is a vote to leave the European Union in the forthcoming referendum.

The Bank blew its cover on Friday when it accidentally emailed details of the project – including how the bank intended to fend off any inquiries about its work – direct to the Guardian.

According to the confidential email, the press and most staff in Threadneedle Street must be kept in the dark about the work underway, which has been dubbed Project Bookend.

The revelation is likely to embarrass the bank governor, Mark Carney, who has overhauled the central bank's operations and promised greater transparency over its decision-making.