"Whilst reach might be enormous, there are questions over resonance: How many people are really paying attention?” asks Ottokar Rosenberger, national manager for eHarmony.

Ottokar Rosenberger, UK country manager of eHarmony, which has not yet advertised on Twitter but is exploring the use of paid-for slots of the social network, thinks advertisers have doubts about how much cut-through a sponsored tweet can actually achieve.