It seems likely that some children will be prepared for the 11+ examinations by experienced and gifted teachers. Other children will have to compete for the same prize with very different expectations and preparation.
Non verbal reasoning plays a part in a number of 11+ examinations. Most non verbal tests look at the ability to recognise similarities, analogies and patterns in unfamiliar designs.
Language knowledge is not supposed to play a significant part on the results - providing that the initial instructions have been understood. The initial instructions may be couched in terms like these:
Each of the questions below starts with a pair of shapes on the left hand side. These two shapes have something in common. Decide what it is, then look at the rest of the shapes in the boxes on the right. Mark your answer with the letter that goes best with the shapes on the left.
Learning to follow instructions may be a major benefit of 11+ examinations.