Is it East Grinstead?
Yes indeed ... just the London line left to the north. West to Three Bridges, East to Tunbridge Wells and south to Horsted Keynes all lost - through that latter has been restored by the Bluebell Railway.
Noting that East Grinstead has the same population as Melksham, I may have wondered why it retained a complete railway to serve it and Melksham didn't keep even a station on the Lin passing through. Amongst the suggestions are (a) its nearness to London and (b) that a Dr Richard Beeching lived there and commuted from there.
Looking "up thread" - yes, Taunton has lost four local services .. but it has retained trains in three directions and not just the one of Barnstaple and of East Grinstead. I did wonder about
Kings Lynn ... and outside the south east about
Bishops Auckland. There are some doubtful cases too -
Whitby used to have train to Redcar, Scarborough and Pickering - just one line remains via Battersby. However, I'm not sure if I would count the Pickering line out of Whitby, since it shares the first few miles with the line that's still open.
Of course, if you look right across the British Isles you'll find towns with a single line where you could have caught trains in three extra directions in the past - to Fenit, Listowel and Dingle, and a city with just a single service remaining and terminating where - from other stations in the city - you could have travelled to Burptonport or Cardonagh, to Strabane or Omagh, and to Stronalar, Donegal and Killybegs.