To combat these issues the Railway Clearing House (an organisation originally set up to share out revenue from joint services between companies) introduced minimum standards for private owner wagons in 1887. Companies that were signed up to the RCH refused to allow wagons that did not meet the standards in their trains, although there was a lengthy grace period for owners to upgrade or replace their older wagons. The operational advantages of the more reliable and modern RCH design were such that several railway companies instigated 'buy-back' schemes for private-owner wagons, whereby the company would buy existing wagons from their owners. Either the railway replaced them with company-owned wagons or the private owner spent their proceeds on new RCH-type wagons. Between 1882 and 1902 the Midland Railway purchased 66,000 private-owner wagons and built over 50,000 of its own wagons as replacements. New and stricter standards were introduced by the RCH in 1909 which required hydraulic buffers and oil-lubricated bearings as well as numerous other details in the construction of the frame, brakes, axles, and suspension that made the RCH's design the basis for virtually every British mineral and goods wagon for the next 30 years. Wagons that complied with the standards carried a plate saying 'RCH'. Although the 1909 design standards were supposed to be fully enforced by 1914 the advent of World War I meant that they were suspended and many non-compliant wagons actually remained in service until well after the Grouping of 1921.