It is true that the UK has good growth rates in British pounds. However, a good part of that is the large decline in the pound against most other currencies. This decline has made British exports (and services and tourism) more competitive. If you were to measure British economic performance in USD or Euro the UK would still be substantially down since Brexit. I know that most people in the UK aren't going to see this as a big thing, but one has only to consider the great Marmite controversy of the last few months to see that there will be a reckoning at some point.