Arrange the sliced beetroot around the edge four serving plates, overlapping the slices to form a circle.
Bring a pan of water to the boil, add the bacon lardons and blanch for 1 minute. Drain and pat dry with kitchen paper.
Heat a frying pan until hot, add the bacon lardons and fry for 3-4 minutes, until golden-brown and crisp. Drain on kitchen paper.
Whisk the English mustard, white wine vinegar and rapeseed oil together in a bowl for the dressing. Season, to taste, with salt, freshly ground black pepper and the caster sugar.
Place the watercress and Little Gem leaves in a bowl and mix together. Add the bacon lardons.
Preheat the grill to high.
Place the goats' cheese rounds onto a grill tray and cook under the grill for 1-2 minutes, or until golden-brown and bubbling.
To serve, drizzle the dressing over the salad leaves and toss well to coat. Pile the salad into the middle of the serving plates. Balance the goats' cheese rounds on to of the salad and drizzle some more dressing around the edges of the plate.