An overhaul of planning rules for the protected area has seen an increase in applications for new houses over the last year and a half.
But overall numbers remain low, prompting concerns about what it could mean for the future of the park and the families living in it.
“It’s been discussed before that we have a rapidly ageing population and the number of households is pretty much static,” said Andy Saunders, a member of the national park’s governing authority.
“Households with no usual residents have gone from 111 to 218 (between 2001 – 2017 and) in the north of the park there’s a lot of housing which is (now holiday) lets.
“And there’s new legislation that (EPC rated C homes) cannot be (rented out), so if we’re not careful those houses will not be let, which allows different socio-economic groups to live in them, and will be converted to holiday lets.
“We need to look at that, the future is not good for our population.”
According to park planning bosses, there have been seven applications approved for new homes in the last 18 months, just shy of the target of eight set in its Local Plan.
Prior to this, the authority averaged just one bid to build every 12 months.
The new policy also placed a greater emphasis on new houses being designated “principal residences”, limiting the scope for second or holiday homes.
However, chief executive Tony Gates has admitted that “anecdotally” a lot of homes are being switched to accommodation for tourists.
Wooler farmer Mark Mather, a member of the authority and a county councillor, warned: “With Northumberland having the highest proportion of tenanted farms, we could potentially see a huge change in our housing and how it’s used, as tenant farmers retire.
“Often they live in quite nice farm houses, worth quite a lot of money in rental value, and I can foresee a big change if they’re forced into retirement.
“These houses seem to be looked at as ideal holiday lets for large families, so potentially our community is going to change dramatically and we need to keep an eye on that.”