I think it's more common than you realise actually.
I know a number of villages where there has been a massive influx of people from London / SE over the last twenty years as they were desirable as a location.
Meanwhile families that have lived here for generations have been priced out - mainly working class types - the only ones who remain live in the small amount of council housing and older middle people have found their kids who have gone away to university can't afford to move back.
There's a definite tension. Most of the time these people will be friendly enough to 'outsider' and won't be as direct as the person in the OPs story.
However because I lived in the area a long time, I am well aware that if I mention this to these groups in conversation, they do instantly change tone and are friendlier especially if they originally assumed I was an 'outsider'. Usually it takes me to raise it unsolicited to take away a grumpy veneer. They will have a conversation about various things and take more time in a different way to newcomers with me.
Indeed DH had a more direct incident over Easter. He was helping out doing something for the community and got someone whinging directly about people moving in etc etc. DH hasn't grown up in the vicinity but he's well aware of the issue. He isn't from the SE - he's from somewhere much more working class. He knows to stress that he 'married in' rather than 'bought in and moved up'. Again whinging bloke changed tone and was much more supportive to the point he started to help DH spontaneously!
It's not all the time, and it's rarely as confrontational. And I know most people who move in, can live here and be completely unaware of the divide because they don't tend to mix with the longer term residents because the social circles tend to be separate. The 'outsiders' tend not to be so heavily involved in the older community issues and if they do get involved (which is less likely) tend to stick to their new things rather than invest in the 'traditions'. DH and I are particularly unusual because we fit in with/ belong to both social circles due to my past and DHs occupation and having a young son. This means we tend to notice the divide much more and it can be awkward at times if you get happen to get stuck in the middle of an issue.
I genuinely believe it exists in any village across the country which has had a significant migration from London / SE. You just don't necessarily see it, as it's got to such a point that the old guard has been so displaced / outnumbered. New movers can be insensitive / oblivious to this sense of 'losing identity'.
Personally I think it's tied up with generational change, and is natural to an extent. Speaking to my friends Dad, a couple of years ago before he died, it's not new. He grew up in the area and was in his 80s. His family moved in during the 1920s from Manchester. They were a family which had made money from cotton and were now moving out of the city for new ventures. This guy was born here but even in the 1970s when he stood for parish elections he faced hostility for being an outsider!
From what I've read, there was similar hostility a generation prior to that when the railway was built and that changed the nature of the area.
The problem is a marked change in population growth and economic affluence which makes it hard to miss for older residents and it's the affluence that grates and lack of awareness/ interest in the history of the place that hurts.
The irony for me is it's this group most opposed to new houses - which might help local residents and stop them being forced out.
I think it's dead complex and difficult to navigate. Places do change. It's normal and change can't be stopped. And some people always dislike change.