I second Franks suggestion.
It was not a secret base though. They landed near a village in Scotland were supposedly Winston Churchill would be staying over at a friends house. The object was to kill Churchill. The plot however was that this was not the real Curchill but a "double". The "kill" succeeded but no man of the German unit ( wich were to immitate Polish paratroopers on excercise) lived to return to the "fatherland" and tell off there "succes"
The Germans wore there real uniforms under the Polish paratrooper uniforms and when a small girl was nearly drowning near a watermill a man from the unit jumped in the water to recue her. By doing this he saved the little girl but died in the attempt and thereby revealing his german uniform wich was identified by the village pastor who witnessed the action. After this all hell broke lose for the German unit and the film ends with a shot of the barge, perhaps Schnellboat or PT-boat,wich would have taken the unit to a U-boat, stranded on a sandbank near the coast.

Kind regards
Wiljan Bakers