The night landing runway is changed on its own schedule, rather than being tied to the 'post-1500' landing runway.
At 6am we nominally change to the 'pre-1500' landing runway, however we tend to land on both until about 0645.
Another question though...on arrival back at LHR on Monday, all arrivals / departures were on 9L / 9R...weather was calm. But all published arrivals are 27L or 27R...so when do the 9s come in?
Not sure what you mean here.....our procedures say we should stay on 27s until there is a tailwind of 5kts. However, if the wind is forecast to go easterly later in the day we might well stay on 09s even though the wind is calm.
The noise restrictions dictate the landing runway on 27s, but the departure runway on 09s.