The news contradicts earlier predictions, as reported by The Wall Street Journal, that suggested agency revenues would drop by an average of 15 per cent.
Council president Kathy Cripps said: 'The agencies were not recession-proof, but the figures prove that PR outperforms the ad industry in times of GDP decline.
'It was a tough year, but most agencies proved very resilient,' she added.
But the rankings do highlight the severity of last year's redundancies.
The total number of employees for firms reporting their figures fell from 22,860 to 18,383 - a drop of nearly 20 per cent.
Cuts at the top 20 agencies were even more severe, with staff numbers plummetting by 24 per cent.
Much of the damage was inflicted by the tech market dive.
Revenues from tech fell 18.4 per cent, from more than £790m in 2000 to £647m in 2001.
Accordingly, the share of agency revenues derived from tech fell from 41 per cent to 34 per cent.
Revenues from the financial sector suffered a similar slide, from £126m to £104m.
Business from other areas held up well, however.
Healthcare was the star performer, with revenues from companies in this sector rising 21.3 per cent to £361m.
Healthcare now constitutes just under 20 per cent of all PR agency business - up from 15 per cent in 2000.
Merging with BSMG helped Weber Shandwick displace Fleishman-Hillard as the biggest firm in the rankings, despite a revenue decline of 21 per cent.