<span style="color: #222222;">The United Kingdom has been in the grip of a cold spell with temperatures plummeting around the country. Three young boys have been killed after falling into an ice-covered lake, as the country recorded its coldest night of the year so far. Heavy snowfall is disrupting air traffic, train networks and roads. Parts of London's underground network were suspended or faced delays, while motorways were gridlocked due to snow.<br />''<br />''The Met Office, recorded temperatures as low as minus 15.7 degrees Celsius in northern Scotland, while it continued to issue weather warnings elsewhere in the country. According to media reports, there were multiple closures on the M25, the UK's busiest highway, which circles the capital.</span><br />