Chop the bacon into pieces and fry until crisp. Drain on paper towels and set aside.
Heat the grill over high heat. Lightly brush the scallops with olive oil and season with salt and pepper. Grilled the scallops until just opaque, about 2-3 minutes per side.
In a small bowl, whisk together the orange juice, vinegars and oil. Season with salt and pepper.
In a large salad bowl, add the watercress and fennel and toss with enough of the salad dressing to coat.
Divide the greens evenly between two or four plates and top with the appropriate number of grilled scallops. Drizzle with remaining dressing and divide the crispy bacon over each. Season with a bit of Maldon salt and more freshly ground black pepper.