<p>Christmas, 1669. In the grip of the coldest winter for years, the River Thames is frozen from bank to bank and London celebrates with a traditional frost fair held on its broad back. Revellers come from far and wide to enjoy the spectacle: an ox is roasted, booths set up and entertainers employed to amuse the crowds enjoying the holiday atmosphere.<br><br>Among the throng is ambitious young architect Christopher Redmayne, escorting the daughte...