The calculated distance (air line) between Newark on Trent and Southend-on-Sea is approximately 124 miles respectively 199 kilometers.
By car or train, the actual journey to Southend-on-Sea is certainly longer, as only the direct route (as the crow flies) between Newark on Trent and Southend-on-Sea has been calculated here.
Air line (approximately)
199 kilometers
108 nautical miles