Which LDZ / Local Distribution Zone you are in has a significant effect on your gas bill. This applies to both the standing charges and the unit rates or price per therm. Unfortunately, it’s also something you can’t change, short of moving your business. Your LDZ also dictates who you will need to contact to upgrade or downgrade your supply or if you are looking for a new supply.
The EM area covers this area

Towns
Alford |
Alfreton |
Ashbourne |
Ashby-de-la-Zouch |
Bakewell |
Barnetby |
Barrow-Upon-Humber |
Barton-Upon-Humber |
Basingstoke |
Belper |
Boston |
Bourne |
Brackley |
Brigg |
Burton upon Trent |
Buxton |
Chesterfield |
Cleethorpes |
Coalville |
Corby |
Daventry |
Derby |
Dronfield |
Gainsborough |
Grantham |
Grimsby |
Heanor |
Hope Valley |
Horncastle |
Ilkeston |
Immingham |
Kettering |
Lincoln |
Loughborough |
Louth |
Lutterworth |
Mablethorpe |
Mansfield |
Market Harborough |
Market Rasen |
Matlock |
Melton Mowbray |
Mexborough |
Newark |
Newport Pagnell |
Northampton |
Nottingham |
Oakham |
Olney |
Retford |
Ripley |
Rotherham |
Rushden |
Scunthorpe |
Skegness |
Sleaford |
Southwell |
Spalding |
Spilsby |
Stamford |
Swadlincote |
Towcester |
Ulceby |
Wigston |
Woodhall Spa |
Worksop |
Counties
Lincolnshire |
Derbyshire |
Leicestershire |
Hampshire |
Northamptonshire |
Staffordshire |
South Yorkshire |
Nottinghamshire |
Buckinghamshire |
Rutland |
The EM Distribution Zone is operated by Cadent