The 85-year-old actress's ill-stricken former co-star, who played her character Dot's on-screen husband Jim Branning, suffered a stroke in 2007 which has left him unable to walk or speak fluently.
When Brown asks her former colleague how his condition makes him feel, 73-year-old Bardon can only respond by whispering: "Oh dear."
Bardon's wife Edna says of Bardon's current state: "He's going the wrong way now. His main pleasure in life is when his grandson Harry visits."
Brown said of her rapport with the actor: "We got on very well. We got to understand each other. We could give each other notes without offence.
"We had a very good rapport and good timing. We laughed a lot, which is nice. It's the best way."
Brown, currently on a six-month hiatus from EastEnders, last week revealed that she visits Bardon "regularly".
Brown's documentary Respect My Elders airs this Thursday (July 12) on BBC One at 10.35pm.
Watch June Brown in the trailer for BBC One's 'When I'm 65' season below: