Marketing budgets over the next 18 months are facing their sharpest falls since the terrorist attacks of September 11 2001, according to a survey widely regarded as a confidence barometer for the broader economy as well as the advertising industry.

The Institute of Practitioners in Advertising’s Bellwether Report, released on Monday, says budgets for the current year have been revised down for the third quarter in succession. The rate of decline “was gathering to a pace not seen since the immediate aftermath of the 9/11 terrorist attacks”, it said.