Whilst we have pretty strict firearms legislation in the UKicon it is certainly possible to obtain the licence for manually operated rifles as collector's items or for shooting. You have to show 'good reasons' for their acquisition, have secure storage (eg a concealed security cabinet), and an approved place to use them if they are to be fired. Also supply addresses of two referees for your character, have no criminal record, supply four photos etc. If your justification is target shooting the police will check your usage with the rifle club. Then you have to pay a £50 fee for the first 5 years and go through the process again every 5 years. This is worthwhile if you are seriously interested.
However our deactivation standards for bolt action rifles are not as severe as in some countries: the barrel has to be slit, plugged, and secured to the receiver with a welded pin so that it cannot easily be replaced. The bolt lugs are weakened, firing pin tip cut off, and receiver feed ramp cut through. Externally the appearance of the rifle is unchanged, the bolt can be manipulated and the gun field stripped and dry fired. As a non-firearm a de-act can be displayed in your living room, den or whatever without restriction. You would be ill-advised to walk about the street carrying it uncovered however as a police 'armed response vehicle' would probably be summoned!
Many thousands of these de-acs have been sold over the last 24 years since they were put on a proper legal footing and they enable people to collect and enjoy guns without the hassle of licencing, and sell them on easily (and often profitably) when necessary. Most of the Lee-Enfields are not rare: often tired and worn out re-imports from overseas which have been fitted with new furniture and other parts.
It is indeed a shame if pristine, rare, or otherwise desirable guns are ruined by de-activation (as has been the case with too many museums) and one would certainly not advocate that but the alternative could well be total destruction. De-activation has at least allowed many Lee-Enfields to survive in some form and give people the pleasure of their ownership.