Fixed family names were adopted in Wales from the 15th century onwards. Previously, the Welsh had a patronymic naming system.
In 1292, 48 per cent of Welsh names were patronymics, and in some parishes over 70 per cent.
The stock of Welsh surnames is very small, which is partly attributable to the reduction in the variety of baptismal names after the Protestant Reformation.
Meaning of surname Aylmer: Allmor a valley or dale