Preheat the oven to 180°C, 350°F, Gas 4.
Cook the Jersey Royals in a large pan of lightly salted boiling water for approximately 20 minutes, depending on size, until tender. Drain and leave to cool.
Place the quail eggs in a pan of cold water, bring to the boil and cook for 3½ minutes, then refresh in cold water to prevent them overcooking. Once the eggs have cooled, peel off the shells and cut in half. Set aside.
Lay the pancetta slices on a non-stick baking sheet and bake in the oven for approximately 6 minutes, until brown. Remove the slices, which will crisp up as they cool. Once cooled, cut into 3cm/1¼in slices.
When the Jersey Royals are cool enough to handle, cut in half. Heat the oil in a sauté or frying pan, add the potatoes and cook until golden brown, then add the butter to give a richer flavour. Drain the potatoes on kitchen paper and place in a serving bowl. Scatter over the pancetta and quail egg halves, season with lots of freshly ground black pepper and serve at once.