Further update having arrived at Reading.
By the time we reached Tilehurst our "sinner" had donned her mask.
On arrival at Reading about 20 left the coach, only one without a mask, no lanyard visible.
Here at Reading it looks like 90% mask wearing, almost all those not doing so look under the age of 20.
BTW▸ - underfoot conditions on the overbridge at Reading are treacherous this morning. It's that phenomenon when warm damp air hits cold black floor tiles turning them into a shaking rink again. Take care!
To be strictly accurate I do not believe that the colour of the floor tiles is relevant.
Footbridges, road bridges, overpasses and similar structures with open air UNDER the structure are more liable to condensation, or to ice if conditions are cold enough.
A road surface upon the ground looses heat only from the upper surface, but a bridge or similar structure looses heat from the upper AND lower surface and therefore becomes colder, quicker in severe weather.
When the weather moderates condensation forms on the cold surface.
If snow falls or ice forms, it is more likely to persist on colder surfaces.