With the arrival of a second television network, it was more important than ever for dealers and members of the public to tune in correctly.  Early sets (and some of today's portables) had a habit of 'wandering off' from the prime location, and it was felt that the only proper way of ensuring a well-tuned set was over a testcard.

Dealers also preferred a testcard (although programmes might have been better for show off a set) as compared to black or white noise.  If nothing else, at least a set in the showroom could be shown to be working correctly before someone spent a month's wages on it.

Before programmes began, a simplified testcard, designed to be used by the 'man of the house' for final tweaking was used over an opening tune.  For the rest of television's downtime, a more detailed card was shown for installers to use in the home to get the new aerial set up correctly.