The record of the National Fruit Collection, at Brogdale in Kent, describes it1:
Originated at Newtown, Long Island, USA. It was recorded in 1817. Fruits have firm, coarse, creamy yellow flesh with a sweet subacid flavour.
Where Newtown Spitzenburg came from.
Sources
Newtown Spitzenburg (accession 1950 - 182), National Fruit Collection, Brogdale, Kent (Defra).
Supports: the description quoted; the use; the fruit's size, shape and colours and the flesh, from the collection's characterisation; the picking time at Brogdale (late october); the other names.