the gesture you're referring to, known as "backhanding" or the "V-sign," involves displaying the peace sign (made by forming a V-shape with the index and middle fingers) but with the back of your hand facing outward. In the UK, this specific version of the peace sign is often considered offensive and vulgar.
The reason for its offensiveness can be traced back to historical origins. During the medieval period, archers played a significant role in English warfare, and when French soldiers captured English archers, they sometimes cut off their index and middle fingers to disable their ability to draw a bow. As a result, the English archers who survived would taunt the French by showing their intact fingers, the same gesture that resembles the modern-day peace sign but with the palm facing outward.
Over time, this gesture evolved into a symbol of defiance and contempt, and it eventually gained an offensive connotation. Today, while many people may not be aware of the specific historical context, the offensive meaning has been passed down through generations, making it a gesture to avoid using in the UK.
It's important to note that cultural meanings and interpretations of gestures can vary across different countries, so what might be offensive in one place might not carry the same meaning elsewhere.