What about Southend?
Central
East
Victoria
Airport
Plus if you include the borough, Shoeburyness, Thorpe Bay, Westcliff, Chalkwell, Leigh on Sea.
You actually got this wrong. The Airport station is just outside the boundary - but you omitted Prittlewell. It is about 200m from having ten, and is thus almost certainly the winner in terms of stations per town.
However, this isn't a fair analysis in my opinion. To give you an idea of why, compare Lichfield with Northampton. Northampton is roughly six times bigger but has only one station against Lichfield's two. And yet, Lichfield is a city whereas Northampton is a town.
It is much fairer to do this kind of thign relative to population. In this sense, all of Northampton - c. 180,000 people - have just one station available to them, whereas the c. 30,000 in Lichfield have two, averaging 15,000 per station; by that reckoning, Northampton should have
twelve!