Not overly the same question but someone who knows the answer to OP’s probably knows the answer to this:
Why did rum become the rationed spirit aboard ships (particularly Royal Navy ships) rather than any other spirit?
Gin is actually a pretty "cheap" drink. (I don't say this to imply the Brits are cheap, but to explain its rise to popularity.)
The juniper berry itself is native to Europe and was used by Egyptians and Romans since antiquity. It grows in Northern Europe, including in England, and near London. It was commonly used in the Middle Ages as a spice substitute for peppercorns, which were very expensive and came from Southeast Asia.
Now when Europeans started distilling alcohol stronger than beer or wine (think 1600s and 1700s), they used inefficient copper stills and it had a lot of impurities and tasted pretty darn nasty, so the Europeans used whatever spices and herbs they could to mask the alcohol's flavor. You see this in a lot of other traditional European beverages, too, like schnapps, akvavit, ouzo, etc.
Gin itself actually originated from the Dutch beverage jenever, named for juniper, which these days is the national and traditional beverage of the Netherlands and Belgium. So it's more than just an English thing. It was brought to England when William of Orange became King William III in the Glorious Revolution of 1689.
William III also disliked France, so he decided to put high tariffs on French brandy, which was the popular strong spirit of the time. Now brandy is made from distilling wine, and wine can't be made in England, so people turned to making local gin in what became the Gin Craze, from 1695-1735. It was wildly popular with the poor blokes of London, leading to the government putting high taxes on it in 1736, which was so unpopular it caused widespread riots. Then a lot of people started making gin at home, and some flavored it with turpentine, which imparts a pine taste like juniper but is most definitely not good for anybody to drink.
Luckily, England has formed a lot more regulations around gin production since then, and the distillation process has improved so it doesn't taste quite so nasty anymore. All that historical ruckus over gin cemented it as something very British, and later the famous "gin and tonic" was invented by the imperial Brits in India who used it to mask the nasty flavor of the quinine tonic they used to treat malaria.