The Anglo-Saxons, who began arriving in southern and eastern Britain as mercenaries during Roman times, are popularly credited with having first drained the Lea Valley marshlands for use as hay-meadows. One account attributes the draining of the marshes to an order in the year 876 (some say 895) of King Alfred the Great, the King of Wessex who united the Saxon kingdoms for the first time. It is very probable that until the late Saxon period the area was marshier and subject to more frequent flooding, and there is indeed what appears to be a drainage channel said to date from Saxon times on Walthamstow Marsh. However, this popular account is more probably based on the known draining of the Upper Lea on King Alfred’s orders, carried out to strand a waterborne Danish army which was attacking Ware; and this is recorded in the Anglo-Saxon Chronicles.
The Lammas grazing system was once very widespread throughout north-west Europe, and survived until recently particularly in Ireland and Scotland (where Lammas Day remains an important Bank Holiday). The practice is clearly pre-Roman, as evidenced by the fact that in most cases the Defence Period is from the Celtic midsummer day (Lughnasa, 1st August, later Christianised by the Saxon church as Hlafmaesse or Lammas) to the Celtic midwinter day (Imbolg, 2nd February, later Christianised as Candlemas, the feast of the purification of the Virgin Mary, although often also celebrated in southern Ireland in honour of Saint Brigid, herself probably a Christianisation of the Celtic Goddess called by the Romans Brigantia - the Romans never conquered Ireland, of course).
Although there were obvious differences between Saxon and Celtic tribespeople (in religion, folklore, customs and language etc.) there were many similarities in their way of life. Everywhere in pre-industrial times the economy was based around food production and trade. So when sizeable Saxon communities arrived and settled down here it is hardly surprising they adopted many native agricultural practices that had stood the test of time, including grazing regimes such as transhumance. Cattle had always been an important part of the Romano-British economy - the Celtic nobility measured their wealth in terms of head of cattle - and were moved seasonally between water meadows and woodlands. In Leyton that meant the Lea Valley marshes and Epping Forest.
In the period between the Romans leaving Britannia and the coming of the Normans, Romanised Britons, Celtic tribesmen and later the Anglo-Saxon villagers lived a rural and agricultural life. Villagers generally farmed the land in common, with strips of land in each of several large unenclosed arable fields being periodically redistributed either by lot or in rotation. Haymaking was a very important activity; hay was needed as winter stores for beasts and was much valued. Common grazing land for cattle and pannage for pigs in the forests was as essential as tillage. The custom of growing grass in hay-meadows in early summer and turning grazing animals onto the mown fields after the hay had been removed is ancient and was widespread. Unfortunately, there are very few written records from this period and it is very difficult to know exactly what rules were in force for seasonal Lammas Grazing on the Common Mead of Leyton and Walthamstow Marshes.