Complex sentence: A few Alderney people elected not to leave Alderney with the general evacuation, howvever boats from Guernsey came and collected them before the German army arrived, on the basis it was best for their personal safety.
Split into simpler sentences: A few Alderney people elected not to leave Alderney with the general evacuation. However, boats from Guernsey came and collected them before the German Army arrived, on the basis it was best for their personal safety.