In a seminar at the Midem music industry conference in Cannes this week, Blur's manager criticised the use of musicians in the advertising industry, with particular scorn directed at Duffy's advert for Coca Cola.
Chris Morrison said, "I think Duffy's Coca-Cola ad was abysmal and I think Robbie Williams on T Mobile was terrible.
"I don't think either of those two things did any favours to the artists' careers or the way they're perceived.
"I think you have to be very, very careful about how you associate with brands," Mr Morrison added.
A clip from Duffy's advert:
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