High Wycombe is probably more expensive than Luton and possibly even Crawley. OK it's not exactly out in the sticks but is a reasonable distance from London. Don't expect much change from 350k for an average house
Harpenden, about 5 miles or so from Luton, where Eric Morecambe lived is one of the most sought after expensive places in the country to live. Luton, by contrast is one of the cheapest places to live in the south. Harpenden won't ever sink and Luton probably won't gentrify for a few decades...
Deliberate policy to keep the housing market inflated which is pretty much was most voters care about. People who own a property are duped into thinking that owning makes you rich.