The surname of ALSTOUN is of two-fold origin. It was an Old English personal name, composed of the elements AEOL (noble) and EALD (old). It was also a habitation name from any of various places called Alston in Lancashire, Devon and Somerset, or from Alstone in Gloucestershire and Staffordshire. ALNODESTUNA (without surname) is recorded in the Domesday Book of 1086, and appears to be the first of the name on record. ALLESTUN (without surname) is documented in County Devon in 1242, and Henry Alston was on record in Cambridge in 1273, and Robert Alston appears there at the same time. Ralph de Alleston of County Salop, was recorded during the reign of Edward I (1279-1307). The rise of surnames, according to the accepted theory, was due to the Norman Conquest of 1066. It is often assumed that men 'adopted' their surnames. Some certainly did, but the individual himself had no need for a label to distinguish him from his fellows. The development of the feudal system made it essential that the king should know exactly what service each knight owed. Payments to and by the exchequer required that debtors and creditors should be particularized. Monasteries drew up surveys and extents with details of tenants of all classes in their services. Any description which identified the man was satisfactory, his father's name, the name of his land, or a nickname known to be his. The upper classes mostly illiterate, were those with whom the officials were chiefly concerned and among them surnames first became numerous and hereditary. Later instances of the name mention Edward Alston and Sarah Hussey who were married in London (no church given) in the year 1624, and John Wittewronge and Clare Alstone were married in London in 1644.

The associated coat of arms is recorded in Sir Bernard Burkes General Armory. Ulster King of Arms in 1884. Registered at Saxham Hall, County Suffolk, and Odell, County Bedfordshire.