In the United Kingdom the use of celebrities in advertising is declining. A new report by WPP research points out only one in eight ads now feature a celebrity, marking a decline in usage from 21 to 13 percent in the past five years. Brand Republic explains the usage in celebrities goes in waves, so we might expect a rise in the next future.

Picking the right testimonial can prove an incredibly powerful move for brand promotion. This is probably what L'Oreal has in mind since it's offering David and Victoria Beckham a multi-million deal to promote its hair care products.