British Airways has tweeted that fog is causing delays and some cancellations at Heathrow Airport.
Fog is causing delays & some cancellations at London Heathrow today. Please check your flight details here http://t.co/aZ9bu1grmm
More top news
The parents of missing Madeleine McCann have said "there will always be hope" in the hunt for their daughter.
The boy was attacked on a bus in south London. Police say he was stabbed in the stomach.
With Donald Trump and Hillary Clinton looking set to become the Republican and Democrat presidential candidates, what happens next?