The dialects brought by the Jutes, Saxons and Angles interacted with the languages spoken by the Celts, Romans and Scandinavians.

In the case of the Celts it is apparent that they were not totally exterminated except in certain areas. A large number of them was assimilated into the new culture. The Anglo-Saxon Chronicle narrates the struggle between natives and the new-comers, and the fact that Britons were annihilated certain in areas such as Andreceaster or Pevensey, although this is an exceptional case. In the East and South-East the Germanic conquest was fully accomplished with fewer Celtic populations left. A large number of Celts fled to the West, where we can find a considerable number of Celtic toponyms. Among Celtic place-names we find;

• Kent – from Celtic Cant or Cantion
• Deira and Bernicia (two ancient Northumbrian kingdoms) which have their origin in Celtic tribal names.
• In the West and South-West; Devonshire contains in the first element the tribal name Dumnonii.Cornwall – Cornubian Welsh
• Cumberland (now part of Cumbria) – ‘land of the Cymry or Britons’
• London – it possibly goes back to a Celtic designation
• The first syllable of Winchester, Salisbury, Exeter, Gloucester,Worcester, Lichfield.
• The earlier name of Canterbury – Durovernum
• Names of rivers and hills; Thames,
• various Celtic words for ‘river’ and ‘water’ in Avon, Exe, Esk, Usk, Dover, Wye.
• Celtic words for ‘hill’; Barr (Welsh bar ‘top, summit’), Bredon (bre – hill), Bryn Mawr (Bryn-hill, Mawr-great), Creech, Pendle (pen-top), crag, luh (lake)
• Others: Cumb (deep valley) => Duncombe, Holcombe, Winchcombe; Torr (high rock, peak)=>Torr, Torcross, Torhill; Pill (tidal creek)=>Pylle, Huntspill; Brocc (badger)=>Brockholes, Brockhall.

A few Latin words were borrowed during the Roman occupation and are sometimes combined with these Celtic terms; castra, fontana, fossa, portus, vicus.

Outside of place-names the influence is almost negligible. There is only a score of Old English words which can be traced back to a Celtic source within which we find to distinct groups; words learned by the Anglo-Saxons through everyday contact with natives, transmitted orally and words introduced by the Irish Christian missionaries, which have a religious nature.

• In the first group we find words such as ‘binn’ (basket, crib), ‘bratt’ (cloak), ‘dun’ (dark coloured), ‘ass’ (from Latin ‘asinus’) and ‘brocc’ (brock or badger), and those describing geographical features such as the aforementioned.
• In the second group we find those terms inherited from Celtic Christianity; ‘ancor'(hermit), ‘dry'(magician), ‘cine'(gathering of parchment leaves), ‘cross’, ‘clugge'(bell), ‘gabolring'(compass), ‘mind'(diadem), ‘stœr'(history), ‘cursian'(curse).

Source: A History of the English Language.

Albert C. Baugh and Thomas Cable (Routledge)