According to a report over at Bleeding Cool, X-Men: First Class (which is being shot primarily in the UK as Matthew Vaughn's last superhero feature Kick-Ass was) are using Sarah Eastel Locations to search for all sorts of properties including the two described below.
"Large cellars with high ceilings ideally within south east."
"Large brutallist building to double as CIA headquarters, for feature film shooting November for 1 month. Anywhere in the UK."
Interestingly, the site also mentions that "...they need a new X-Mansion". They point out that some of the earliest stories featuring Professor X and Magneto had them aligned with US Secret Service. Could this be the same thing? Be sure to share your thoughts in the usual place!