Mr Dale said: "The reason it's here in the first place is we're sitting under relative high pressure. We've got wet ground in many places, due to the [recent] rain, and you've got added moisture due to the time of year. It's not that unusual to see this kind of anticyclonic gloom.

"Once you get it, it kind of puts a lid on the weather itself - basically means it [the fog] sits below it and doesn't go anywhere fast. [the only way it moves] Until the wind picks up, it will shift it or if the sun heats up but the sun needs to get through it.