But this was no baby – he was at least three, if not four, sucking like an infant on a plastic pacifier as he helped his mother pack the shopping into bags.
Dummies serve a useful purpose when babies are small; my daughter had one for a while to help her sleep, and I have no real feelings either way about whether they're 'right' or 'wrong'.
But in my opinion a child who walks and talks should no more have a dummy that they should be wearing baby-gros and drinking from bottles – they're just too old.
I quite appreciate the difficulties inherent in weaning children off comforters, but who's the parent, here? They need to get a grip and just take it away.
Mum-of-two Victoria agrees with my approach, expressing her concern about the detrimental effect dummies can have on speech development. She blames parental laziness for the prevalence of pacifier-addicted pre-schoolers, saying there's really no excuse for children aged three and four to still be sucking on dummies.
"Children that age simply don't need a dummy as a soother," she says. "The parents are just too lazy to wean them off it."
Victoria isn't anti-dummies per se; both her sons had them as babies, but when they reached the age of two she took them away. She concedes that it's not always easy, but says you have to explain and negotiate with your child.
"My youngest knows dummies are for babies and can just about grasp that he's not a baby any more," she says. "He needed a bit of persuasion, but eventually he put them in the bin himself."
Another mother I asked is equally biased against older children with dummies in their mouths. "When I see three-year-olds being pushed around the shops with a dummy in, it makes me cringe," says Emily. "I can't help but feel the parents are lazy, and that they're not talking enough to their children."
Emily's view is that whilst a dummy might be acceptable for night-time soothing, by the time a baby reaches its first birthday they should be leaving the dummy at home when they go out.
"I just feel that if they are awake and at an age where they may start talking, then they shouldn't have a dummy in their mouths," she explains. "How can they shout 'car!' or 'train!' with a dummy in?"
Jenny is a teacher, and I wondered how she felt about dummies from a learning perspective. Like Emily and Victoria, Jenny thinks dummies are too often misused by parents who want peace and quiet.
"I personally feel that pacifiers are unnecessary past the age of one as they inhibit children's speech development," she says. "Children learn through watching and repeating; they can't practice the necessary mouth movement to learn correct speech when they have a lump of moulded plastic in their mouths."
So if dummies are damaging to speech development, then why do we see so many older children with them? Yvonne, mum to two almost grown-up children, disagrees that dummies are harmful. "My boys are now 20 and 15 but I'm fairly sure they were often seen with a dummy at the ages of three or four," she says. "It's not done them any harm!"
She recalls being a little worried about it at the time, but says that what seems like a really big deal at the time really doesn't matter in the grand scheme of things.
This is, of course, often the way with parenting; you fret over potty training, weaning and a million other milestones, and can only with the benefit of hindsight see how little it really mattered.
Someone who agrees with Yvonne's laid-back perspective is Vickie, who used a dummy herself until she was four and now encourages her own five-year-old to have her pacifier whenever she wants it.
"It's her most precious possession – I wouldn't take it away from her just because it makes people uncomfortable to look at her with it," Vickie says. "If I did take it awayI know she would find another way to fill the need she has, whether that meant sucking her thumb, grinding her teeth, or biting her nails."
Vickie's view is that children will wean themselves off whatever comfort mechanism they use when the time is right. "Until then," she says, "I don't plan on trying to shame her for needing it."
What do you think?
Should children be weaned off dummies by the time they can walk?
More on Parentdish: How old is too old for a pushchair?
More:Advice And Health
Suggested For You
SUBSCRIBE AND FOLLOW
Get top stories and blog posts emailed to me each day. Newsletters may offer personalized content or advertisements.Learn more