Is this a statement or a question? If it's a statement, it's untrue. Nobody in Britain would represent the way they say these words as 'bawth', 'pawth' or 'glawss'! We do not pronounce these words with the same 'aw' sound as in 'awful' . If you want to transcribe how these words are pronounced in the south of England, a closer approximation would be 'ah'. For example, in RP, as in other southern English accents, the words 'bath' and 'barn' both start in the same way - with the sound 'bah', followed by the end consonant. Better still, check any good dictionary that has an audio function and IPA transcription: paw /pɔː/ path /pɑːθ/ If you look at these transcriptions and listen to 'paw' and 'path' spoken in a standard/southern British accent, you'll see that they have very different sounds.

There are many different regional accents in the UK. Many words can sound different in the North or South of the country, and of course in Scotland and Ireland too.

I don't know about the U.K. In the town I live in, in the United States, near Boston, people who grew up in town indeed use a vowel sound like the "o" in "not" in words like "laugh," "bath," and "aunt." I say them like the "a" in "bad" or "cat." I pronounce the words "aunt" and "ant" exactly the same way; they do not. They say "ant" the same way I do, but they say something like "ont" for their mother's sister. The local pronunciation is not upper-class, it's just the local pronunciation; and it is almost certainly Irish, not Boston Brahmin. P.S. The "Dictionary of American Regional English," which documents this kind of difference, is 5,544 pages long and is published in five volumes!

These sound a bit "posh". Usually foreign learners seeking a British accent hope to imitate what is known as the "BBC-RP" pronunciation.