The agency made a return to the top slot for the first time since February, bagging 20 deals worth £9.36bn.
The Deal Watch figures, compiled exclusively for PRWeek by corporate information service Zephus, show Brunswick overtook previous league leaders Financial Dynamics and The Maitland Consultancy, which rank second and third respectively.
Brunswick advised on the completion of Imperial Tobacco's £3.2bn takeover of Germany's Reemtsma Zigarettenfabriken.
But the biggest deal of the month went to Finsbury and Financial Dynamics, advising on the £5.2bn deal between German energy giant RWE, which owns Thames Water, and the UK's largest energy supplier Innogy Holdings.
Finsbury, in fourth place in the table, advised Innogy, while FD was hired in March to help RWE gain support for the bid, which is expected to close in July.
May also saw B&Q parent Kingfisher lodge its unwelcome offer for the 45 per cent stake it does not already own in French DIY chain Castorama.
The Maitland Consultancy in the UK and Euro RSCG in France are helping gain backing for shared client Kingfisher's deal.
Cubitt Consulting made its first ever entry in the Deal Watch table, taking fifth place advising South African Breweries (SAB) on its £3.8bn bid for Miller Brewing.
The agency, which was hired by SAB in October last year (PRWeek, 19 October 2001), is handling all PR surrounding the brewer's agreed deal for Miller from parent Philip Morris.
Bell Pottinger Financial scraped into the top ten after a two-month absence advising easyJet on its £374m purchase of rival low-cost airline Go.
Deal Watch is produced according to publicised deals involving at least one UK company.
DEAL WATCH - MAY 2002 RANKING
Rank Financial PR Company No of Deal Value
Deals pounds bn
1 Brunswick 20 9.36
2 Financial Dynamics 16 8.37
3 The Maitland Consultancy 10 6.68
4 Finsbury 6 6.03
5 Cubitt Consulting 1 3.83
6 Gavin Anderson & Co 6 2.40
7 Smithfield Financial 1 1.24
8 GCI Financial 4 0.594
9 Cardew & Co 3 0.588
10 Bell Pottinger Financial 4 0.481
Source: Zephus Corporate Finance Knowledge (www.zephus.com)