The UK?
Cops can carry anywhere; whether they've been instructed to do so and allowed to as public servants is different.
Japan?
Warning; incoming nerd-dom
The Japanese learned of gun powder from the Chinese and had comparable metallurgy with Europe.
The arquebus came to Japan by way of the Dutch as early as the 1540s, and a new class of warrior joined the ranks of any warlord who was worth his salt.
They were called the ashigaru, the 'lightfooted', and they wielded a tanegashima or teppō gun.
Within ten years of introduction, hundreds of thousands of teppo matchlock rifles were in the hands of ashigaru as the common rabble a smaller daimyo could call to arms and train quickly and cheaply.
Japan in this period was locked in a series of civil wars (depending on if you think of a singular Japanese people as warring under different kingdoms or not), punctuated by periods of relative peace during the Sengoku era (1460s to 1603).
Matchlock firearms were introduced about halfway through this period, and while initially they suffered the same problems early firearms did everywhere; slow, unreliable, succumb to humidity, real heavy, they didn't stay like this for long...
Designs improved, and improved quickly, and by 1567 Takeda Shingen proclaimed to his vassals:
Think about this.
In Japanese feudal society, the definition of a warrior is the Samurai.
From a very tender age, he has been beaten, starved, disciplined, rewarded, fed, humiliated, honored, crushed, and molded into the best archer his eyes and arms will let him be, the best runner and pilot of a mount his legs will let him be, the most cunning swordsman his wits and steel will let him be.
His nutrition is well taken care of like a prize horse, he mind wants for nothing but to build a legacy by absolute service to his Daimyo.
His sword is one of the most valuable possessions anyone could have.
His armor is as much a piece of craftsmanship and showmanship as it is a brute utilitarian tool of slaughter.
He is the pinnacle of Japanese warcraft, romanticized in widely read pop-fiction and high brow kabuki theatre, (along with Ronin, who are effectively just wandering, 'roguish' Samurai)
He can now have his stomach blown open, his horse ripped to shreds from under him, and his armor shattered by illiterate peasant children with teeth rotting in their head.
It totally changed warcraft.
Pope Urban II banned the use of crossbows in 1096 for much the same reason; because skilled knights were being killed by common peasants, totally disrupting the balance of power on battlefields.
To drive home how much of a deal this is - some context:
One of the most powerful clans of all of Japan were the Takeda, who trace their origins to the 56th Emperor of Japan, Emperor Seiwa, born in the year 850.
When he was nine, he and his grandfather (the Regent - - think Tywin to his Joffrey, though without the dickheadishness), ordered the construction of this massive war shrine.
It's basically a small castle/town.
These are not simple people.
This is a refined, urbane civilization with a history which extends in continuity far longer than any contemporary royal house of Europe, still scrabbling over the remains of the true Roman Empire, with Byzantium in decline, shit in the streets and Vikings sacking London and Canterbury.
The Takeda descend from this ancient line of Emperors - -gods among men.
Takeda Harunob Shingen is head of the Takeda clan by 1540 (this is a ruling class family of elites with a continual line of succession and wealth build up from the year 850, remember), and he is a brilliant tactician, wherein by the Battle of Mikatagahara in 1572 he has adapted the Samurai from primarily horse mounter archers to a combined force of lancers, infantry and ranged fighters - - opposing enemies were slaughtered by this use of combined arms, area denial, fire and movement tactics, etc.
You simply do not fuck with the Takeda clan.
Shingen dies of an illness, May 13 1573.
His less capable spawn, Takeda Katsuyori, takes over.
By 1575, the clans are warring again (more like some more), and Tokugawa Ieyasu, who had been so bitterly defeated by the Takeda, is allied with Clan Oda.
Now, here's the deal - -Oda Nobunaga, head daimyo of the Oda clan had pretty much been wrecking shit left and right, as one of the power contestants.
But he simply doesn't have the numbers to match Takeda cavalry/lancers/archers, despite having more foot soldiers.
So what does he do?
He assigns three guns to everyone under his command that he can, imputing a doctrine of relief-to-load, and return-to-fire, bifurcating each unit between preparing to shoot and shooting who will stand in lines, with the group that has fired immediately going to load by crouching down, letting the group behind them fire and then immediately crouching to load, letting the group behind them do the same, and hopefully by the end of this, the front group are moving back up into a firing position and the second group are nearly done re-loading. Oh, and they're doing this from behind miniature pallisade fortifications or otherwise running around on the battlefield - - this is the beginnings of dedicated volley fire/salvo coordination.
It is 15-fucking-75.
What happens?
12,000 besieging Takeda cavalry are mowed down by 3,000 Samurai Arquebusiers under the command of the Oda clan's elite guard.
4 to 1 and they get butchered
Some of the most celebrated and respected Samurai, generals and archers, are being ripped apart by accurate ranged fire sending one monme [8.5mm] to 100 monme (48 mm) shells zipping through the air, horses, armor, and men.
The Takeda clan was effectively ruined, though some would go on to important positions in the Tokugawa Shogunate.
When Hideyoshi unified Japan and invaded Korea?
You bet he was making great use of arquebusiers/Samurai wielding teppo.
The Japanese were ultimately repelled, but with one quarter of their forces armed with the most advanced rifles of the day, they took Seoul in 18 days of landing at Pusan.
But the defeat the hands of the Koreans was humiliating, and it showed Japanese leadership that the gun did not make the State invincible abroad; only mortal at home.
So what did the Tokugawa Shogunate do?
It banned the guns
First was Toyotomi Hideyoshi's "sword hunt", but eventually in 1675, gun control came, with the introduction of classes of licensure, issued by the government.
You could have:
ryôshi teppô, for hunting and sporting purposes
odoshi teppô, for protection from animals/protecting crops
That second category, by the way, isn't to be loaded with shot, but just powder. and also, rarely issued and discouraged:
yôjin teppô - -weaponry for self defense;
Hunters were allowed to own their guns all the time - - Farmers were not, because they didn't need guns, and "seasonal" permits started to become the norm.
If you don't need guns at this part of the year, why should the Shogunate issue a license? If you don't have a pressing need to be a Yojimbo, why should the Shogunate license you?
Sound familiar?
By the early 19th century, the Shogunate begins to fear the consolidation of power among the peasants, or worse, the Ronin, and begins mass inspections and registration and confiscation of firearms it deems "not necessary" for the people to own.
Admiral Perry shows up in 1854, the samurai are outmodded and replaced by a national conscriptional army in 1868, and by the 20th century, Japanese civilians do not own arms in any appreciable number, and the days of the people being able to ruin a warlord's day with powder and a strong shoulder is done.
The Tokugawa Shogunate didn't ban guns to keep people safe; they banned guns to ensure their political control, won, in part, with firearms, could not be taken away by the rabble
Contrast this to what another group of people were up to in the late 1700s -- when Kentucky longrifles and Pennsylvania squirrel guns barked out death onto vastly more professional Royal fusiliers and top-notch German mercenary companies, ending the control of the single largest and most powerful Empire at the time over a group of troublesome tea-dumping farmers.