Irvine sent a fairly strong side to face Morecambe but the match was over before the half hour mark as Preston notched up three quick goals.
St Ledger scored in the opening minutes from a corner whilst Hawley and Mellor added to their pre-season tallies. Preston also kept a clean sheet to match with the previous three games they have played this pre-season.
Irvine now faces his toughest test this Summer as Everton take on North End in Preston's only home game during the run in to the season.