Hertfordshire Police and Crime Commissioner David Lloyd has called for changes to law to stop knife and violent crime making its way to the county.
The number of knife crimes reported in Hertfordshire dropped in 2018 when compared to the previous year - despite seeing an overall increase in England and Wales.
In total, 37 per cent of knife and offensive weapon offences resulted in an immediate custodial sentence in 2018, according to the Ministry of Justice, compared with 20 per cent in 2008.
The number of knife offences recorded in Hertfordshire have more than doubled in the last four years and, in a 12-month period through to September 2018, almost one third were committed by children - the highest percentage in the country.
Police are urging residents across Hertfordshire to surrender any unwanted knives anonymously, without risk of prosecution.