The West Yorkshire fog was particularly bad in the year 1926 and the inhabitants and guests of Downton Abbey knew they were in for a long weekend. They couldn't know how long it would eventually become.
Violet, the Dowager Countess, would have told them about the last time this occurred – Lord Grantham had barely been eight years old at the time and was therefore unlikely to remember in particularly vivid detail, even if he had been present – but alas she had passed away some four years earlier and was thus finally silent on matters such as these. Many within the household considered this a silent blessing and though she was much missed, her tongue was not. But without her guidance they were unprepared for the fog that descended upon them and though a mere change in the weather was not so problematic that it was unbearable, they were undeniable stuck.
The saving grace was that the food supplies were high and, assuming the fog did not hover for several months, they would not starve. And they had intended to be in each other's company this weekend anyway, so really things were not too bad. It was not as though anyone could control he weather and all of them agreed that the forecast had been so vague anything could have happened. No one had known after all.
Except for one.
One who had overheard the Dowager Countess, so many years ago now, talking about the changed that led up to the fog descending and had known they were all to be trapped this weekend. Cut off from the rest of the world, the phone-lines knocked out by the wind the previous week and with smog so thick even the bravest chauffeur would not dare to drive a car into it.
One who had planned it all.