I travelled to Hastings on that day too, the first day of electric trains on the line. I think it was amazingly cheap for travel between Tonbridge & Hastings for £1 or some such price? There were things going on at most intermediate stations, but inevitably most headed for Hastings, and the trains were packed. Staff in shops in Hastings were overheard saying it was busier than a bank holiday.
I remember massive queues on the return, with long waits just to get from the station approach to the platform. As well as the line's Jaffa Cake 411s, suburban EPBs were pressed in to service to help shift the huge crowds, as mentioned by Mike99 above. There was the odd moan, but generally people were out to enjoy themselves and good-natured.
All in all, a very visible demonstration of the "sparks' effect" on day one of the electrification.
I'll have you know, I'm pretty nutty too!