William succeeded in making England essentially French, but it wasn’t ever going to be possible to convert a whole population in one go. What he did create was an ‘us and them’ mentality, the Anglo –Saxon peasantry separated from the Norman ruling classes by wealth, power and language.
Through history the English and French have spent a lot of time being joined at the hip and we share a common heritage. Like it or not, they really are our cousins across the sea
Like the remnants of a Celtic heritage that still linger across Western Europe, it’s true the ‘us and them’ mentality has stuck with the English right into modern history. Quite possibly it’s an engrained memory, much like the engrained memory that makes a baby instinctively cling to a washing line. It may be that the English choose to find reasons not to like the French because subconsciously the choice is made to blame them for every working class hardship of the last 1000 years. But this is only one half of the argument.