It has borders with Warwickshire , Leicestershire , Rutland , Cambridgeshire , Peterborough , Bedfordshire , Buckinghamshire ( including the Borough of Milton Keynes ) , Oxfordshire , and Lincolnshire ( England 's shortest county boundary : 19 metres ) . The county town is Northampton . It has boundaries with the ceremonial counties of Warwickshire to the west , Leicestershire and Rutland to the north , Cambridgeshire to the east , Bedfordshire to the south-east , Buckinghamshire to the south , Oxfordshire to the south-west , and Lincolnshire to the north-east â `` England 's shortest county boundary at 19 m. The county town is Northampton .