* Q1 gross sales up 18 pct to 7.3 bln stg, beating forecasts
* Net client cash flows below forecast, at 500 mln pounds
* Outgoing CEO Roberts sees "sound performance" this year (Adds detail, background, CEO comment from statement)
By Carolyn Cohn
LONDON, May 14 (Reuters) - Gross sales at Anglo-South African financial services firm Old Mutual rose an above-forecast 18 percent to 7.3 billion pounds ($11.50 billion) in the first quarter, boosted by acquisitions, inflows and market gains.
Analysts in a company-supplied forecast had expected a 7 billion pound rise in sales for the quarter ending March 31, on a constant currency basis.
Old Mutual, which has a majority stake in South African bank Nedbank, bought UK financial adviser Intrinsic and money manager Quilter Cheviot, enabling it to target wealthy clients following UK pension reforms.
Nedbank also took up a 20 percent stake in African bank Ecobank, while Old Mutual bought a majority stake in Kenyan insurance firm UAP Holdings.
"While economic growth remains relatively weak in South Africa, our businesses continue to deliver good performance," Chief Executive Julian Roberts said in a trading statement.
"We expect continued sound performance for the current year."
Old Mutual said last month it was appointing Standard Bank executive Bruce Hemphill as chief executive, replacing Roberts. Hemphill is expected to take over in the fourth quarter, Old Mutual said.
While the gross sales figure surprised to the upside, the firm's net client cash flows were 500 million pounds, however, lagging a 1.8 billion pound forecast, the company said.
Funds under management, meanwhile, rose 10 percent over the quarter to 351 billion pounds.
$1 = 0.6350 pounds Reporting by Carolyn Cohn; editing by Simon Jessop