I really believe that the following article is really great on why underspending in european projects should be always welcome. At last someone the british raised the issue and highlight that a successful project is not always the project that spends all its budget, considering also that most of the budget for european projects of duration 2-3 years is estimated one year before the official launch of the project. Have a look on the following link and please feel free to comment on it.
http://www.breitbart.com/london/2015/01/27/eu-misusing-british-aid-money/