Information on the number of tests carried out is provided in the following table:
Police force area Total tests Avon and Somerset 27,300 Bedfordshire 7,800 Cambridgeshire 12,300 Cheshire 20,200 Cleveland 8,100 Cumbria 8,400 Derbyshire 31,000 Devon and Cornwall 10,700 Dorset 7,000 Durham 6,100 Essex 25,300 Gloucestershire 7,100 Greater Manchester 19,900 Hampshire 38,400 Hertfordshire 7,300 Humberside 5,600 Kent 32,000 Lancashire 10,200 Leicestershire 15,400 Lincolnshire 11,300 London, City of 700 Merseyside 5,000 Metropolitan Police 61,500 Norfolk 4,800 Northamptonshire 3,200 Northumbria 9,800 North Yorkshire 8,600 Nottinghamshire 8,200 South Yorkshire 6,500 Staffordshire 13,700 Suffolk 10,600 Surrey 9,500 Sussex 15,200 Thames Valley 15,400 Warwickshire 5,500 West Mercia 8,000 West Midlands 6,600 West Yorkshire 16,900 Wiltshire 7,400 Dyfed-Powys 6,700 Gwent 1,600 North Wales 24,200 South Wales 16,700 Total 577,600 1 Following a comparison between the number of positive breath tests reported by each police force in 2004 and the number of court proceedings for drink/driving related offences, it became clear that there was under-reporting in a number of forces. As a result Essex, Hertfordshire, Kent, Lancashire, South Yorkshire, Staffordshire, Dyfed-Powys, Gwent and South Wales, court proceedings figures have been substituted for the positive breath test figures. Similar adjustments were also made to various forces data between 1998 and 2003. Note: Every effort is made to ensure that the figures presented are accurate and complete. However, it is important to note that these data have been extracted from large administrative data systems generated by police forces. As a consequence, care should be taken to ensure data collection processes and their inevitable limitations are taken into account when those data are used.