In the UK, ITV’s advertising revenue was down 42% in April,, external while Fox in the US has seen revenues halve. It is a similar picture in other markets, because there are many products that are just not selling at the moment. So why advertise them?

Take the car industry – sales in the UK in April fell 97%, and are at the lowest level since 1946. They also fell by almost 50% in the same month in the US.

It may seem obvious therefore that car advertising is a waste of money. But cars are still being advertised – albeit to a lesser extent – on TV, on social media, and even on some billboards.

That is because the advertising and marketing industries have long memories, and worry that their customers don’t. Companies with brands that have been around for decades, and which are worth billions, don’t let them die in a recession.

“Brands are reminding people that they exist,” says Andrew Stephen, L’Oréal professor of marketing at Oxford University’s Saïd Business School. “Research shows time and time again in a crisis that turning off advertising altogether slows down the recovery.”

So some businesses will always maintain advertising, no matter how bad things get, as Prof Lambrecht explains. “During the 2008 recession, Procter and Gamble and other similar companies kept their advertising constant. Firms try to stay in the consumer’s mind, even if consumer spending falls. It pays to keep your brand in the consumer’s eye.”