In Leeds during the early 20th century, the local council had spent about £1 million (equivalent to £ in ) in acquiring older, inadequate back-to-back houses for demolition, while continuing to build improved ones of a similar style until 1937, despite being outlawed in 1909 when it was decided that houses should be of an overall higher quality. By 1926, Leeds had 72,000 of these houses, of which 32,000 were described by Dr Christoper Addison as being "abominations", having been condemned as unfit for many years by that time, despite still being lived in; only 12,000 (less than 17 per cent) were given a moderate health pass by Neville Chamberlain's Unhealthy Areas Committee. Other cities had smaller numbers, such as Bradford (33,000) and Nottingham (5,000) respectively. MP Sir John Birchall described Leeds in 1930 as having "an unenviable notoriety for its back-to-back houses", although popularity among residents had increased. He unsuccessfully proposed in 1930 to permit the construction of back-to-back houses in blocks of four, given that back-to-backs were generally cheaper to build than standard through houses and that having two external walls per property would alleviate the ventilation concerns that plagued earlier residences.