Inside the Cambridges ‘code names’ they have for each other including George calling himself Archie

ok.co.uk:

The Cambridge family have a set of 'code names' they use for one another, with Kate Middleton and Prince George both previously giving theirs away accidentally.

Prince William, 39, and Kate, 40, are believed to both have fake names that they use will out and about, and it appears they've also given Prince George, eight, Princess Charlotte, six, and Prince Louis, three, their own fake aliases too.

The Duchess of Cambridge once gave away one of her secret names during a shopping trip in Wales, when she and Prince William were residing in the country after getting married.

The couple rented a farmhouse near the seaside resort of Rhosneigr in Anglesey as, at the time, William was based as a search and rescue pilot at nearby RAF Valley.