It used to be clear: the West End 'opening night' was the night that the critics attended, so did the celebrities and investors, and the reviews duly appeared the next morning (hence the unseemly scurry of departing critics as the lights faded). Those were the days of real opening nights and real overnight reviews. Nowadays, though, it's got a lot more complicated " partly in the guise of making it easier for critics…
SOURCE: The Stage at 02:00AM on July 6, 2012