The consultancy's work on behalf of gas pipeline operator Lattice contributed to its monthly total of four deals worth more than £7bn.
National Grid's proposed friendly bid also catapulted Incepta's Citigate Dewe Rogerson to second place, advising on eight deals worth £6.6bn.
According to the figures, compiled exclusively for PRWeek by corporate finance information service Zephus, Citigate also advised on Unilever's £250m sale of its Mazola cooking oil and corn products business to ACH Food Companies.
Brunswick came third in the table, produced according to publicised deals involving at least one UK company, working on 14 deals totalling £5.7bn.
The firm worked on some of April's biggest deals, including Scottish Power's £2.1bn sale of its Southern Water division to First Aqua - a group of private investors and Brunswick client.
Tulchan, founded by former Brunswick partner Andrew Grant, advised on the opposite side, for Scottish Power, securing its place in the top ten.
WPP-owned Finsbury took fourth place, handling PR for Shell Resources and its £4.3bn bid for Enterprise Oil.
The European Commission gave Shell the go-ahead to buy British oil explorer Enterprise after the initial offer was lodged early last month.
Gavin Anderson & Co claimed eighth place, largely through its work for Enterprise Inns.
Serial acquirer Enterprise announced intentions to take over Laurel Pub Holdings' 1,860 managed pubs, just a year after buying 439 outlets from Morgan Grenfell Private Equity and 431 from Scottish & Newcastle.
Tavistock Communications climbed into the top ten after a six-month absence, working for Vodafone and its completed acquisition of a further stake in Spain's second-largest mobile phone group, Airtel Movil.
While the market remains depressed, financial agencies are in store for a flurry of IPOs over the summer, as HMV and Focus Wickes head for flotation, with speculation that directories business Yell and retailer Homebase will follow.