Holland & Holland offers the take-down option on their bolt rifles and has for many, many years. They no longer use an interrupted barrel thread. That sort of system, and systems with barrels that unscrew, will loosen over time. Instead H&H went to a system whereby the barrel and action remain joined. In the H&H system the front magazine screw is unscrewed and the barreled action gets lifted up from the front and disconnects at the rear of the action tang. The front magazine screw has a keeper so it doesn't get separated from the magazine and lost.

I have used the system and I will tell you it is excellent. If you look on the underside of an H&H bolt rifle and examine the front magazine screw you can immediately tell whether or not it has the take-down option. The front magazine screw is made larger than the rear and it is conveniently turned with a coin the size of a USA quarter dollar. Accuracy and zero are retained because the barrel never leaves the receiver.

Here you can see an H&H rifle with take-down option: Cased H&H take-down rifle

You can look at the back of the action on this rifle and see the modification that allows it to disconnect: H&H takedown rifle