Rush-hour commuters listened in fascination yesterday as a rail company gave the most erudite excuse to date for a sudden rash of breakdowns and delays.
Announcers explained that the wrong type of atmospheric pressure had jinxed the much-hyped £350m fleet of new trains on the former "misery line" between London and Essex's dormitory towns.
Outdoing its long list of famous predecessors - the wrong kind of leaves, snow, rain and even dew on the line - the problem led to a failure of oil pressure on 18 Electrostar 357 trains run by the company c2c between Fenchurch Street and Shoeburyness. A spokesman said that the "fine and delicate workings" of the engines were unexpectedly dished by a sharp change in weather which saw barometers soar.
Regular passengers, mostly professionals with a reasonable grasp of science, were given a five-star explanation, including details of how the glitch affected the pantographs, or overhead current collectors. The c2c spokesman said that the rise in atmospheric pressure - an invisible force which also affects cricket bowling techniques and tennis backspin - had been exceptional.
"Oil pressure plays a very important part in the running of the engines on these trains and this pressure is determined by atmospheric pressure," he said. "The rate of change in atmospheric pressure in the c2c train area this morning was more than twice what it was yesterday. This led to an airlock which, in turn, led to the falling down of the pantograph which collects power from the overhead wires."
The problem, which led to long delays as other services backed up, has caused previous but less dramatic problems with the Electrostars, which were hailed last year as bringing "the comfortable, safe and reliable railway that passengers have a right to expect in the 21st century".
The spokesman said: "We have been working with our engineers to introduce a modification to avoid this kind of problem, but it has not been installed yet."
Atmospheric pressure is the weight exerted by the air (an average one kilogram per square centimetre, or 14.7 pounds per square inch), which rises and falls when temperature change alters the distance between molecules in air.