This is just the modern equivalent. I'm not sure why the BBC is publishing an article about it. The general idea of dropping in a modern power-train with more power and less maintenance has been "a thing" for as long as some rich people have liked classic cars.
Considering these cars only get used on weekends with clear weather, nothing else planned and rarely get driven more than a couple hundred miles at a time (for a bunch of reasons that should be immediately apparent to anyone who has driven a classic car daily or long distance) electric conversions make perfect sense. With gasoline engines these cars tend to be magnets for lack of use problems. Converting to electric also makes good cores more available to the people who want originality while making the converted vehicle more conveniently usable for the people who want that so it's a win all around.
Edit: Lol, downvoted in <2min. I'm sorry (in the "sorry, not sorry" sense of the word) I'm not going to be a fanboy and say this is the greatest thing since sliced bread. This is something that people have been doing for a long time that is moving upmarket and becoming more commercially available and is a natural progression for this market niche because it is a fit for these users.
The price? If you have to ask...