Winemakers worry labels will mislead the public while sales of cheaper product soar as austere times bite.Life is sweet for England's growing legion of winemakers. Sales are booming; awards are flooding in, and critics are being won over. Even the French – with a careful eye on their own harvests – have deigned to note that there is an unusual buzz of activity in vineyards across the Channel. There is, however, a cloud on the horizon, a phenomenon almost as irksome as a corked Nyetimber Classic Cuvée.