Possible silly question (though not as silly as not asking it and getting it wrong): What's the ice factor going to be? In Middle Earth the main roads are clear, but the backstreets still have enough patches of frozen slush and black ice to warrant studded tyres, and pavements/cyclepaths are down right treacherous. I know That London escaped the worst of the snowpocalypse, but...?
(The Met Office suggests that the current cold spell is due to finish at about the same time the ride does.)