Davids vs Goliaths: Are the new fast food pretenders really any more authentic?

‘Authenticity’ is the new byword in design for fast food brands as the giants of the sector face up to the threat of Byron, Five Guys and Shake Shack. But, suggests Silas Amos, some of these new pretenders may be just as artificial as their bigger brothers whose future lies in simply being themselves. Illustrations by David Sparshott.