The Department for Environment, Food and Rural Affairs (Defra) has recruited 1,200 people to help the department get through Brexit.
Defra has grown more than 65% since the EU referendum, according to a new report by think tank Institute for Government.
The report 'Preparing Brexit: How Ready is Whitehall' looks at the huge amount of work that has taken place over the last two years at government level.
New departments, new functions and thousands of new staff have gone from nought to one hundred miles an hour, working on the thorniest issues Whitehall has faced in decades.
The shape and size of departments are changing, in some cases very significantly. Defra has recruited more than 1,200 Brexit roles, added by March this year.
But it is also one of the departments most affected by Brexit. With 80% of its work affected by Brexit, it needs to support negotiations, repatriate regulatory functions, help with border preparations and design, legislate and implement new systems for agricultural support, fisheries management and environmental protection.
The report follows a parliamentary Committee's conclusion that Defra faces an "unprecedented challenge" in preparing for Brexit.
The Public Accounts Committee report released in May says preparations for Brexit are being hampered by the "pervasive uncertainty" over the UK’s future relationship with the EU.
The report says this leaves not only the department but also farming and rural businesses in the dark about exactly what they need to do to prepare.
This means that Defra is having to work up options for the three different scenarios—deal, no deal or transition. The report labels this "time consuming and costly".
Over £2 billion has been allocated by government to fund Brexit preparations up to March 2019.