His web site is still making the claim and Guido's isn't making the counter claim so I think this maybe Lammy 1: 0 Guido
It was Guido then...?
If that is the case then there is a video somewhere of him debunking the Harvard claim... 
Actually I don't know but I searched Guido several ways and came up with nothing. As Lammy still has the claim on his site then he'd surely have been challenged by his electoral opponents if it was wrong
I think the truth about Lammy is he has very sus morals but is likely very intelligent at times and fuckwitted way too often