"Nick is paid £100,000 more than me for what is essentially the same job," he said. "That shouldn't detract from what the women are saying – they have a genuine grievance. But there is a wider problem."
Both men present Radio 4's Today Programme. But according to a report released earlier this year, Robinson is paid up to £300,000, while Webb receives less than £200,000 - despite having joined the BBC six years earlier than Robinson.
But Robinson - who was listening to Webb's remarks - defended his pay.
"There are other factors, largely because I was recruited from ITV where I was on a much higher salary than my BBC colleagues," he said.
And both agreed that the gender pay gap is about more than money.
"It really isn't. It's about respect, status and worth," said Robinson. "That's why it's so serious, and why, rightly, it is being taken seriously."
Earlier this month, it was revealed that men working for the BBC earn an average of 9.3% more than women, and take up more than their fair share of the top jobs.
But while this is clearly unfair, the BBC is actually better than average in ensuring equal pay. On average, across the UK, men earned a shocking 18% more than women.
BBC director general Tony Hall, has said that the BBC should be 'an exemplar of what can be achieved when it comes to pay, fairness, gender and representation', and has pledged to close the pay gap by 2020.
He may face some difficulty. Two weeks ago, Radio 2 head Lewis Carnie said that if women were paid less, it was because they deserved less.
"We wouldn't care what anybody is - gender, sexuality or ethnic origin – it's totally irrelevant," he told the Evening Standard. "What's important is the talent, and they're paid according to that."
The government has ordered all charities, private and public sector employers with 250 or more employees to publish their gender pay data by April 2018. Fewer than one in ten have done this so far.
The gender pay gap is at its widest at the top of the career ladder, with male managers being paid 26.8% more than their female colleagues, according to research from the Chartered Management Institute and XpertHR. That means that women managers are getting an average £12,000 a year less.
"Some people have tried to explain the gender pay gap away as being the result of different working hours or individual career choices," says XpertHR content director Mark Crail.
"But when the analysis is based on the pay of more than 100,000 individuals in well over 400 organisations, it is clear that the pay gap is a very real fact of life for UK managers."
The 10 top earning celebrities
The 10 top earning celebrities
At the age of 55, critics have been insisting that her finest days were two decades behind her. Her latest album sold fewer than 1 million copies, and her recent singles have failed to make the impression they once did.
But Madonna has silenced the critics - raking in an astonishing $125 million in one year. That's $25 million more than her nearest rival. Her $305 million wold tour was the major money maker, but her fashion and perfume brands helped too.
This is Madonna's biggest-earning year of all time - surpassing her previous record in 2009 of $110 million.
The veteran director had a hit with Lincoln last year, but the bulk of his $100 earnings comes from royalties from his earlier works. It can't hurt to have the Raiders of the Lost Ark franchise and the Jurassic Park films quietly making money for you. He also makes a slice from the Universal Studios theme parks. The combination means he's up a place in the rankings from last year.
The British 'Shades of Grey' author has faced harsh criticism for her writing style, but she is living proof that sex sells (70 million copies worldwide and counting). With earnings of $95 million this year she's not only the highest-earning author of the year, she's the third-highest-earning celebrity too.
The original shock-jock is pulling in $95 million a year by being the biggest name on US radio. He also made a rumoured $15 million as a judge on America's Got Talent - which has helped push him up from seventh place on the list last year.
Simon Cowell, the second Brit on the list, is still holding fast to his earning power - despite some ratings problems in the US. The X Factor and Got Talent format are worldwide sensations - all earning a small fortune for the TV mogul and soon-to-be father who brought home $95 million in a year. It has pushed him up from tenth place in the list last year - leapfrogging the likes of James Patterson and Michael Bay.
With earnings of $91 million, America's favourite author is reaping the benefits of being both very popular and incredibly prolific. Apparently one in four of all hardback books sold in the US are written by Patterson, and he continues to add to his body of work at an incredible rate - which has helped push him up from eighth to sixth place in a year.
With earnings of $90 million, Beck's various roles as a TV and radio host, conservative political commentator, author and businessman have seen the money flooding in. His official tagline is 'The Fusion of Entertainment and Enlightenment' - so there is a small chance that the money and fame (and moving up from 11th place on the list last year) may have gone to his head.
Earnings of $82 million put the Transformers director in the upper-echelons of the big earners. His blockbuster action films haven't always been a big hit with the critics, but have pulled in the crowds, guaranteeing him big money. He took a bit of a hit this year - with his earnings almost halving from a year earlier (when he was the second-highest paid celebrity). However, Transformers 4 should have him back on top next year.
Making $80 million this year, Bruckheimer's ability to produce Hollywood hits is certainly paying off. Having a back-catalogue that features the Pirates of the Caribbean franchise doesn't hurt. However, he could do with another mega-hit soon as he's down from fourth place on the list last year when he made $35 million more.
Her earnings of $80 million would have been even more if she hadn't had to pull out of much of her tour after suffering a hip injury.
Oprah Winfrey, meanwhile, came in 13th - knocked off the top spot last year, when she was bringing in $165 million a year, and seemed unassailable.