The language died out as an everyday language at the beginning of the 19th century. A recent revival of interest is based on the Middle Cornish period.There are a few people who speak it but it does not have the status of Welsh. I don't even think it has TV programs in that language (unlike Scots Gaelic) either.(I'm sure someone will correct me if I'm wrong).
There are Cornish representatives who make a speech at every Welsh National Eisteddfod each year, just like those from other Celtic countries.
My first language is Welsh but I don't understand Cornish. A few words of Cornish are similar to other Celtic languages ('agus' is the word for 'and' just like in Gaelic.) but it would not be understood by other Celts either. An example would be the first line of the Lord's prayer..
our Father, which art in heaven.
ein Tad, yr hwn wyt yn y nefoedd...Welsh.
ár n-atheir atá ar neamh...Irish Gaelic
ar n-athair a tha air nèamh...Scots Gaelic
ayr ain, t'ayns niau....Manx
agan tas ny, us yn nef...Cornish.
Wrythoug is VERY Wrong...Welsh NEVER died out, even though the English tried their best by forbidding Welsh children (on pain of punishment [look up Welsh Not]) to speak in their native tongue. English was 'forced down the throats' of Welsh people (in their own country!!). Welsh people have proudly ensured that the language has now got equal status with English in Wales; indeed in some parts, like here in Gwynedd, all the council's business is conducted through the medium of Welsh ( with translations available for the [few] non-Welsh speakers.
People like wrythoug and A.Z. don't like this fact at all...they would like one world language..English...well, tough!..it ain't gonna happen!