Unlike other railway companies in the London area, the Met was able to develop land for housing. After World War I they promoted housing estates near the railway with the "Metro-land" brand and nine housing estates were built near stations on the line. Taking advantage of the Treasury guarantees electrification was extended north from Harrow to Rickmansworth and a short branch opened from Rickmansworth to Watford in 1925. In the 1920s more powerful electric and steam locomotives were purchased and Metropolitan Railway stations were redesigned by their architect Charles W Clark.