KML is from Wikidata The HP postcode area, also known as the Hemel Hempstead postcode area, is a group of twenty-four postcode districts in England, within eleven post towns. These cover north-west Hertfordshire (including Hemel Hempstead, Berkhamsted and Tring) and central Buckinghamshire (including Aylesbury, High Wycombe, Beaconsfield, Amersham, Chalfont St Giles, Chesham, Great Missenden and Princes Risborough). Mail for this area is sorted at the Home Counties North Mail Centre in Hemel Hempstead.