The money manager collected net inflows of 3.6 billion pounds, including 2.9 billion pounds into its retail funds. Performance and foreign exchange gains added about 4 billion pounds to its assets during the first quarter.

The merger of an Old Mutual property fund into Henderson's UK Property fund in January also added 470 million of assets.

"Our first quarter flows were boosted by the announcement of European quantitative easing in January," Andrew Formica, chief executive of Henderson said in a statement.

"Increased client demand for European assets has coincided with a sustained period of excellent investment performance from our core European products," he added.

The firm also said that it has agreed to sell its 40 percent stake in TH Real Estate to TIAA-CREF for 80 million pounds. The transaction will complete in June.

(Reporting by Nishant Kumar; editing by Carolyn Cohn)