The calculated distance (air line) between Kirkby in Ashfield and Southend-on-Sea is approximately 136 miles respectively 219 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 Kirkby in Ashfield and Southend-on-Sea has been calculated here.
Air line (approximately)
219 kilometers
118 nautical miles