Nick Clegg was left squirming today as he was grilled on the Coalition's free school meals policy by a nine-year-old boy.
Rohan had the Deputy Prime Minister on the ropes with detailed statistics and objections to the flagship Liberal Democrat measure.
At one point during the encounter on his regular LBC radio phone-in Mr Clegg suggested, with a hint of desperation: "You probably need to go back to class."
The youngster, who said he was calling from his school in south London, started off by complaining that his own school meals were "unhealthy".
"I was wondering why you had decided to introduce free school meals, which is a very expensive product, when at my school they are quite unhealthy and the evidence shows they don't make children achieve or behave better," he said.
Mr Clegg replied: "The evidence shows that it is in fact extremely helpful.
"So in the schools where this has been introduced in the past ... not only does it save mums and dads money - about £400 a year to pay for the lunchtime costs - not only is it good for your health...
"I'm sure this is not the case for you, Rohan, but quite a lot of children go to school with lunch boxes that don't have healthy food in them - I don't know, a slice of white bread and a fizzy drink. It's better to have a proper cooked hot healthy meal with vegetables and so on...
"It's good, isn't it - it's nice when the class eats together."
A seemingly disconcerted Mr Clegg, inadvertently referring to the schoolboy as "Ryan", then attempted to move the discussion on by asking: "What kind of lunch do you eat?"
But Rohan insisted: "I do think it's important to eat well, but a lot of schools, I think, a lot of the parents could already afford to pay for those meals. So I was wondering whether perhaps you could just target it to the areas where parents can't afford to pay for the meals better."
Mr Clegg said: "Actually the children who benefit most are the children who are poor, who are not wealthy... "
However, Rohan broke in to suggest they would "already be entitled to free school meals".
And when the Lib Dem leader argued that in many areas poorer children were not entitled to free school meals, his inquisitor responded: "Couldn't you just target it to their areas, rather than doing it for the whole country where a lot of people could afford it?"
A chastened Mr Clegg - whose own middle son, Alberto, is nine years old - seized on a sound in the background, commenting "I've just heard your class bell go."
He added: "You really should go into politics - you're one of the most articulate nine-year-olds I've ever come across."
But Rohan refused to let him off the hook, saying: "Just one more thing ... at my old school we have to use the gym for school meals which meant that my younger sister can't do string group and a lot of people at my old school would be missing their lessons in the gym."
Mr Clegg shot back: "But they all have to eat lunch anyway, don't they?"
Rohan responded: "But they wouldn't be using the gym."
The Deputy Prime Minister pointed out that he did not know the circumstances at Rohan's school, but insisted it was not a widespread problem - only to be told: "I think probably quite a lot of schools with this space problem ... My old school is ready, but there are effects for the school that aren't as good as we might want."
Mr Clegg, who ruefully remarked that Rohan sounded "quite exceptional in so many respects", suggested that he might want to go away and read the detailed evidence.
But that only prompted the schoolboy to deploy figures.
"Surely, couldn't you spend some of that money on another project?" he asked.
"Because I have seen the evidence and it wasn't very big, the percentage point increase - it was only 1.9 in one of the trials. And also it was bigger for Key Stage 2 than Key Stage 1."
The Lib Dem leader described him as a "very impressive boy", and raised suspicions that he had been primed by an adult.
"You clearly have someone working with you on this ... which is excellent, excellent," he said.
However, Rohan quickly dismissed the idea. "I did it on my own at home," he said.
Seemingly eager to wrap things up, Mr Clegg said: "You probably need to go back to class."
Rohan, who did not give his surname, said his favourite subjects were maths and science. He disclosed that his lunch yesterday was: "Brown bread sandwiches with minestrone soup, with beans in it and some vegetables, and the salad on the side."