The calculated distance (air line) between Beaconsfield and Southend-on-Sea is approximately 59 miles respectively 94 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 Beaconsfield and Southend-on-Sea has been calculated here.
Air line (approximately)
94 kilometers
51 nautical miles