I took a look at that IFS household earnings scale (thanks for the link) and our monthly net income, after council tax has also been taken away, places us in the 90th percentile of the UK. So I suppose that would make our household high earning, and we're bringing in approximately twice the £65k in the OP's question.
The IFS scale leaves out the very high earners, however, because it would distort the distribution too much. So if you included the Magic Circle partners, the investment bankers, the media presenters, the consultants with lively private practices, some of whom live in our neighbourhood, we would not appear at the 90th percentile! I can see why people can be high earners but not feel they are.
And, as others have said, earnings aren't related to expenses. We don't have a big mortgage, but we do have a university-aged child, and so our expenses include rent, utilities and other expenses for a whole separate 'household'.