Bring a large pot of salted water to a boil. Boil potatoes until tender but still firm, about 15 minutes. Drain, cool and dice.
Place eggs in a medium saucepan and cover with cold water. Bring water to a boil and immediately remove from heat. Cover and let eggs stand in hot water for 10 to 12 minutes. Remove from hot water, cool, peel and dice.
Place bacon in a large, deep frypan. Cook over medium high heat until evenly brown. Drain and crumble.
In a large bowl mix together the potatoes, eggs, bacon, olives, 1/4 cup spring onions, mayonnaise, sour cream, salt and pepper. Increase quantities of mayonnaise and sour cream as necessary to create desired consistency. Garnish with remaining spring onions.