Peter Schrijver has theorized that Old English breaking developed from language contact with Celtic. He says that two Celtic languages were spoken in Britain, Highland British Celtic, which was phonologically influenced by British Latin and developed into Welsh, Cornish, and Breton, and Lowland British Celtic, which was brought to Ireland at the time of the Roman conquest of Britain and became Old Irish. Lowland British Celtic had velarization like Old and Modern Irish, which gives preceding vowels a back offglide, and this feature was loaned by language contact into Old English, resulting in backing diphthongs.