For what its worth CAA statement 11 Sept:
“The CAA will continue to issue and reissue pilots' licences when they are lost, damaged, when details need to be changed or pilots' privileges updated as we do now. Over time, this would include removing references to EASA - a purely cosmetic change. There will be no requirement for licences to be re-issued for any other reason meaning that there will be no change to this process.
“The CAA also strongly refutes any suggestion that we are concerned about our ability to provide safety oversight to the UK aviation industry should no-deal be reached between the UK and the EU. The safety of passengers, crew and those on the ground remains our absolute priority and nothing has changed in this respect.
They did re-issue all pilot licences a few years ago to include "ELP"