No 10 cancelled a meeting between the UK and Greek PMs after comments to the BBC about the sculptures.
Lisa Wilkinson, who is also the granddaughter of the chain's founder, said she had let people down.
People are being told to prepare for potentially "hazardous conditions" amid freezing weather.
Valdo Calocane pleads guilty to killing Barnaby Webber, Grace O'Malley-Kumar and Ian Coates.
Virgin Atlantic is flying the first big passenger plane using 100% alternative fuels from London to New York.