If you thought last week was as cold as you could bear it, brace yourself. Forecasters say the worst is yet to come, and this winter could be the harshest since the Thames froze over more than three centuries ago. Temperatures for December are the coldest on record, with the average reading close to minus 1c – almost six degrees below normal. And with forecasters warning that this winter’s ‘mini ice age’ might last until mid-March, this winter could be the worst since 1683-84 when a fair was held on the Thames.