The calculated distance (air line) between Caerphilly and Southend-on-Sea is approximately 169 miles respectively 272 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 Caerphilly and Southend-on-Sea has been calculated here.
Air line (approximately)
272 kilometers
147 nautical miles