The shadow justice secretary was hosting a phone-in on Monday, to discuss calls to scrap the term “BAME”.
A woman, named Jean, joined in the conversation to tell Lammy: "You will never be English because you’re African-Caribbean.”
Asking her why he could never be English, she repeated “because you’re African-Caribbean,” adding: “I can’t say I’m African-Caribbean.”
Lammy then provided a “little bit of history” on the situation, telling her: "Britain 400 years ago started going out into the world, it colonised and conquered a lot of the world, a lot of the world has ended up coming back to the mother country.”
He then explained that a DNA test revealed that he “had Scottish in him”.
Continuing, amid Jean’s occasional “mm hmm”s", he said: “Here I am, having grown up in this country, have been born of this country and, actually, the truth is there’s a myth there’s one English ethnicity, there’s not.
"England has always been a country where Huguenots, Danes, all sorts of people have passed through. So when you say you are English I’m not saying that that doesn’t mean something to you, and matter hugely.”
However, he continued: “For me, the fact that I was born here and the fact that my sensibilities are English mean I want to claim that heritage as well."
He then said he was “very comfortable” describing himself as black British, but was also immensely proud of his Caribbean roots.
Jean then chimed in to say that it was fine for Lammy to describe himself as British, but “you’re not English".
She argued that if she, as a white woman, had been born in the Caribbean she would not call herself as such, to which David pointed out: "You probably don’t realise that in countries like Barbados there are significant white Caribbean populations who have been there for hundreds of years.
"And they are significantly more Caribbean than I am."
Jean responded: “Well all I can say is the world is polluting everybody,” insisting: “You are what you are and you are where you’re born – it’s your inheritance.”
Lamenting her use of “pollution”, Lammy continued: “It’s a negative way to describe the fact that people meet one another, they fall in love, they have kids, they move borders - sometimes through war, sometimes through economic reasons - and they become what they become when they are of that country.
"And just as you can be in America and be African-American, or you can be Italian-American, or you can be Irish-American, how is it that here in England, you can only claim that Englishness if you are white?"
The MP has been widely praised for his calm and respectful handling of the situation which, many have acknowledged, would have left them incandescent with rage.
Deputy Labour leader Angela Rayner tweeted: “This is disgraceful. The way that Black Britons have to justify their Britishness or Englishness is absolutely disgusting.
“Solidarity with David Lammy who dealt with this impeccably. David is just as British or English as I am and he's the best of Britain and the best of England.”
Meanwhile, Scottish Labour leader commented: “This is so well-handled David Lammy, but sad that it still has to be explained. Our children will be less tolerant of racism and more harshly impacted.
“I was delighted to hear about your Scottish blood though.”
And former MP Paula Sherriff wrote: “Let’s call this out for what it is - out and out racism. David Lammy is typically polite and reasonable in response but it’s nonetheless sad that these extreme attitudes persist in 2021.”
Other Twitter users offered similar responses:
Lammy himself has since commented on the exchange with a characteristically calm response.
Retweeting a clip from the broadcast, he said simply: “Don’t ever tell me I’m ‘not English’.”
Lammy later addressed the reaction to the clip. You can read more here.