It was due to the ballast not being replaced after the weekend engineering works, hence leaving platform 2 out of use for a few days (Three days, I seem to recall...).
It didn't cause too much grief, just meant we couldn't berth any stock in East Grinstead sidings. Led to some variations, but all longer trains.
The reason for the trains starting from Lingfield was the amount of stock the try to jam down the Grinny line in the peaks, they had to make some room and did this buy turning trains round short of Grinstead.
Cheers,
El Insider.