The English language is used by nearly half of the population, with the Scots and Welsh speaking the largest number, according to the National Centre for Research and Evaluation (NCRE).
In Wales, the Welsh have the largest population, followed by the Scots, and the English, the National Institute of Health says.
The research shows that people from the UK have more than twice as many Scots as Welsh speakers.
It also found that the Scottish and Welsh share a more complex relationship with the English language, with a higher proportion of speakers using the words English, English, and Welsh.
It said there was no difference between Scots and English speakers in how they use the words “mother”, “motherfucker”, and “fuck”.
This is a problem, said Professor John Hatton, an English and Scottish language specialist at University College London.
“This is one of the few areas where the differences between English and Welsh are really striking,” he said.
He added that it is a shame that the BBC is showing a lot of British people as not knowing their own language.
British children have less English than Welsh, and a growing number of children are being taught to speak English as a second language by the BBC.
However, Mr Hatton believes the BBC should take a long-term view, to see how they can reach a more culturally inclusive audience.
In the meantime, he said the British public have been educated to be tolerant of other languages.
“This needs to change, and it needs to happen in the next decade,” he told BBC Radio 4’s Today programme.
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