There are two sign languages native to the British Isles. British Sign Language (BSL) is used by the Deaf community of England, Scotland, Wales and Protestant signers in Northern Ireland. Irish Sign Language (ISL) is used by members of the Deaf community in the Republic of Ireland (McDonnell 2004) and Catholic signers in Northern Ireland (Matthews 1996). The two sign languages are distinct, not believed to be genetically related, and mutually unintelligible. Both are natural, living community languages. Although the two sign languages are unrelated, there have been some mutual influences in relation to lexical borrowing; although they are both independent of the English language used by the hearing society surrounding them, both exist in a minority relationship with English and consequently show some evidence of English influence.

As the social and educational experiences of the British and Irish Deaf communities have been very different historically (and still are, to a certain extent), the social aspects of the two languages need to be described separately. However, the linguistic features of BSL and ISL, and, it should be noted, other European sign languages, are sufficiently similar for a single basic description of the grammar of BSL to be applicable to ISL, unless noted otherwise.

BSL and ISL differ from English in three main ways:

• they are visual-spatial languages (not sound-based like English);

• they are unwritten (not having the great literary tradition of English); and

• they are numerically minority languages, with users numbered in the thousands (ISL) or tens of thousands (BSL) (not the approximately 60 million British and Irish English users).