What does blinkered mean in British slang?

"Blinkered" is not really a slang term in British English, it's a more standard word with a specific meaning. It comes from the blinders that are placed on horses to stop them from seeing things to the side, focusing their attention on what's straight ahead.

Therefore, "blinkered" means:

1. Limited in outlook or understanding: Someone who is "blinkered" is unable or unwilling to see things from different perspectives, they are focused on their own limited point of view.

2. Narrow-minded: Similar to the above, but emphasizing the lack of flexibility and openness to new ideas.

Example:

* "He's so blinkered, he can't see that his plan is flawed."

* "Don't be so blinkered, there are other ways to do this!"

It's important to note: "Blinkered" is generally used in a negative way to describe someone who is stubbornly refusing to consider alternative viewpoints.