According to the latest Government Census, the population of the UK in 2001 was 58,789,194.
England 49,138,831 (83.6 pc); Scotland 5,062,011 (8.6 pc); Wales 2,903,085 (4.9 pc); Northern Ireland 1,685,267 (2.9 pc).
It has grown 17 pc since 1951, but the growth rate is smaller than the average growth for EU Europe (23 pc); the USA 80 pc; and Australia 133 pc. To get a hugely detailled picture of large towns area by area, (but you'll have to do that maths yourself) visit the Government's stats website:
http://www.neighbourhood.statistics.gov.uk/tables/
eng/TableViewer/Wdsview/dispviewp.asp?ReportId=184&area=noload