The post and railway town of Redhill (RH postcode area) which did not exist in the early 19th century has become during the 20th century and beyond a major town on land formerly in Reigate and Merstham, expanding into the latter into the 21st century with little buffer between the three settlements today; the three forming a conurbation keeping boundaries close to the far side of the Greensand Ridge and North Downs, to the south and north respectively. Even in the 19th century rural and a rotten borough, Gatton apart from Upper Gatton within the M25 has become part of Reigate and of Redhill, indivisible from those towns while retaining Gatton Park occupied by a co-educational independent school, The Royal Alexandra and Albert School. A fraction of its land has been opened up to the public by the National Trust but is now approximately half residential land in Reigate and Redhill.