The London Stock Exchange's fledgling clearing business was the stellar performer in the first half of the year pushing the exchange group's income up 20 percent to 386.5 million pounds.

The LSE said on Wednesday interest drawn from loans to clients through its clearing business rose 225 percent to 54.3 million pounds in the six months to the end of September, driving profit up 38 percent to 214.3 million pounds and earnings up 48 percent to 47.6 pence per share.

Key highlights include a very good performance from post trade, an area we highlighted in 2009 as a core focus for us and which is now making a significant contribution to both Group revenue and growth, said chief executive Xavier Rolet in an emailed statement.

Revenue at the LSE's main capitals markets business rose 13 percent to 159.8 million pounds, while data services was up 6 percent to 89 million and technology sales rose 1 percent to 24.8 million pounds.

The LSE results came as fellow British trading firm ICAP , which matches buyers and sellers in the bond, currency and swaps markets, reported flat revenue for the same period of 867 million pounds.

(Reporting by Luke Jeffs; Editing by Erica Billingham)