It's the day when GDP data is announced for the third quarter of the year.
My sources tell me the news is positive - in other words it's growth and not recession. But they also tell me this is largely for technical reasons. In other words, some accounting wrinkles may help the situation.
It looks to me like this may well be a quarter where the real tale will be in the subsequent revision of this first estimate in a few weeks time and that today's news is being massaged for all it's worth to give a period of grace before the Chancellor's autumn statement.