The TV presenters were guests on The Graham Norton Show, where they recounted their experience ahead of their final interview with the then-Prince of Wales.
McPartlin shared an amusing anecdote about encountering Charles while wearing a robe, leading to an embarrassing conversation about pruning roses.
Donnelly admitted they 'took it a bit far' with wine in their room, resulting in a request to be quiet.
The duo also discussed their new podcast, Hanging Out with Ant & Dec, while other guests on the show included Claire Foy, Joe Keery, and Tinie Tempah.