I have not tried these yet because it is still too hot here in sunny Texas so I am wishing for cooler weather...
The difference isn’t just the name, however. The Brits take great care when it comes to their potatoes — and the results really are much crispier on the outside and fluffier on the inside than the typical American variety.
The article says slicing a cross shape about 1/4-inch thick into each potato.
Then Bake the potatoes longs: 400 degrees for two hours.
After taking the potatoes out, carefully cut deeper into the slices you made initially, then put the potatoes back in the
oven for 10 more minutes.
This is what I got from article:
https://www.thekitchn.com/jacket-potato-22943799