A prominent brick tower is identified by P Sowan as an observatory for surveying the line of the Merstham Tunnel on the London & Brighton Railway Company line constructed in 1838-41. The structure is described and the possibility of its present appearance resulting from later modifications is discussed. (SIHG 76) Four substantial square brick pillars linked at the top with iron ties are identified by P Sowan as the remains of an observatory for the surveying of a tunnel on the London Brighton & South Coast Railway's Quarry Line, which opened in 1899. (SIHG 76) TQ291 546