LONDON -- It's the dark days of one of the rainiest British winters on record. So some London commuters were surprised to hear their trains had been delayed because of the sun.

Rail operator Southeastern tweeted Tuesday that "we had severe congestion through Lewisham due to dispatching issues as a result of strong sunlight." The company said low winter sun was hitting monitors at an angle that meant the drivers could not see them.

Almost 1 million people travel to London by train every weekday -- and commuters are used to hearing a wide array of excuses for the frequent delays.

Past culprits have included "leaves on the line" and "the wrong type of snow."