Having emigrated from Southend in the mid-seventies, I'm not sure of the current situation, BUT
Southend has (d) TWO main-lines into London. Both were fast and reliable, though jam-packed in rush-hour.....one of the reasons I moved "oop north" to enjoy a less populous area.
Never remember meeting sir Freddie but Father was a good friend of "budgie" Jack Laker ,who once chauffeured us to Clacton to Southend and back in his Daimler Majestic Major. lovely family and didn't deserve the dirty tricks campaign that scuppered Skytrain.