Indeed, 'A Very British Scandal' takes inspiration from actual incidents and characters. It presents a fictionalized account of true occurrences to make it more engaging for the audience.
There was a pair of lovers. They grew up together in a small town. The boy had a terminal illness. He hid it from the girl. As they were planning their future, his health deteriorated rapidly. He passed away before they could fulfill any of their dreams. The girl was heartbroken. She visits his grave every day, and that's a very sad but true love story.
Sure. Once there was a man who found a lost wallet on the street. Instead of taking the money inside for himself, he used the ID in the wallet to track down the owner. He returned the wallet intact, and the owner was extremely grateful. It was a simple but very true story about honesty.
Often, it's the emotional impact. For example, a very true story about a person overcoming great adversity, like a serious illness or poverty, can be memorable because it makes us feel strong emotions like hope and admiration.
It is indeed a true story. The show takes elements from actual incidents and presents them in a dramatized form, maintaining the core essence of what happened in reality.