Not only in the UK, but in the English language in general, abbreviations for groups of words or expressions are frequent. Thus, a very common way of saying goodbye is with a simple "x", which is equivalent to "Kisses." In the photo we see, for example, the abbreviation "OMG", which is equivalent to "Oh my God!" and it means "My God!" You have all the information in: «Customs in England«.
You have all the information in: "Customs in England".