"Hard-up" Defra

The Department for the Environment, Food and Rural Affairs (Defra) has underspent its budget by almost £750 million since it was formed in 2001. The Telegraph describes the deprtment as "hard-up" and mentions that due to cutting £200 million from its budget to cover the levies imposed by the EU for the late payment of agricultural subsidies, Defra has decreased spending in other areas, like coastal defence schemes.

Why hasn't Defra used the money underspent to finance its extra costs instead of taking away spending already allocated to other projects? Is that the result of bureacracy and incompetence? It seems to be that underspending is an easier option than considering how to put the available money to a good use and on how to allocate it to projects that need it most.