I find it a great film and the production very interesting
http://www.imdb.com/title/tt0074452/trivia
a lot of interesting stuff on there
filming locations:
Berkshire, England, UK(East Anglia)
Charlestown Harbour, Charlestown, Cornwall, England, UK(Alderney Harbour)
Charlestown, Cornwall, England, UK(Alderney)
Church of St Margaret, Mapledurham, Berkshire, England, UK(East Anglia church where the villagers are held hostage)
Cornwall, England, UK(Channel Islands)
Goods Yard, Rovaniemi, Finland(railway yard)
Mapledurham House, Mapledurham, Berkshire, England, UK(Prime Minister Winston Churchill taken to house)
Mapledurham, Berkshire, England, UK(Village of Studley Constable, Norfolk)
Newquay, Cornwall, England, UK(near) (Lansvoort Airfield)
Pier House Hotel, Charlestown, Cornwall, England, UK(George and Dragon Hotel where Liam Devlin is thrown out)
RAF St Mawgan, Newquay, Cornwall, England, UK(Lansvoort Airfield)
Reading, Berkshire, England, UK(East Anglia)
Rock, Cornwall, England, UK(beach & dunes)
Rovaniemi, Finland(railway yard)
Twickenham Film Studios, St Margarets, Twickenham, Middlesex, England, UK(studio)
Warfield Hall, Forest Road, Newell Green, Berkshire, England, UK(US Rangers headquarters)