1921 Census of England and Wales, General Report with Appendices, Table 8 : " Administrative Counties (Including County Boroughs) arranged in order of Population, 1921".

Administrative
County.		 Population. Administrative
County.		 Population. Administrative
County.		 Population.
Lancashire 4,927,484 Yorks, North Riding 456,436 Suffolk West 108,985
London 4,484,523 Monmouthshire 450,794 Lincolnshire (Parts of Kesteven) 108,250
Yorks, West Riding 3,181,174 Lincolnshire (Part of Lindsey). 408,698 Flintshire 106,617
Durham 1,479,033 Worcestershire 405,842 Isle of Wight 94,666
Essex 1,470,257 Hertfordshire 333,195 Pembrokeshire 91,978
Warwickshire 1,389,977 Cornwall 320,705 Lincolnshire (Parts of Holland) 85,254
Stafford 1,348,877 Northamptonshire 302,404 York, City and County of 84,039
Middlesex 1,253,002 Berkshire 294,821 Isle of Ely 73,817
Glamorganshire 1,252,481 Wiltshire 292,208 Westmorland 65,746
Kent 1,141,666 Suffolk, East 291,073 Brecknockshire 61,222
Cheshire 1,025,724 Cumberland 273,173 Cardiganshire 60,881
Surrey 930,086 Shropshire 243,062 Huntingdonshire 54,741
Southampton 910,252 Buckinghamshire 236,171 Anglesey 51,744
Gloucestershire 757,651 Dorsetshire 228,160 Montgomeryshire 51,263
Northumberland 746,096 Bedfordshire 206,462 Soke of Peterboro. 46,959
Derbyshire 714,662 Sussex, West 195,810 Merionethshire 45,087
Devonshire 709,614 Oxfordshire 189,615 Radnorshire 23,517
Nottinghamshire 641,149 Carmarthenshire 175,073 Rutlandshire 18,376
Sussex, East 532,187 Denbighshire 154,842    
Norfolk 504,293 Carnarvonshire 130,975 Total 37,886,699
Leicestershire 494,469 Cambridgeshire 129,602    
Somersetshire 465,710 Herefordshire 113,189    
Yorks, East Riding 460,880