* Half-year profit of 188.4 mln pounds beats forecasts * Platform reports net addition of 84,000 clients * CEO urges investors to stick to long-term approach (Adds CEO comments from call) Feb 1 (Reuters) - Britain’s biggest retail stockbroker Hargreaves Lansdown posted on Monday stronger-than-expected half-year profits and a record number of new clients, in a further sign of surging interest in online trading by small investors. After retail platforms grappled with frenetic trading in some U.S. stocks last week that was spurred on by social media chat rooms, Chief Executive Chris Hill said Hargreaves was urging clients not to get caught up in short-term moves. “We have been monitoring what is going on in the markets. We have not yet restricted trading in any form but our advice to clients has always been to take the long-term approach,” he told Reuters. Britain’s IG Markets and other platforms for small-time investors have imposed restrictions on GameStop, AMC Entertainment and other stocks at the centre of a trading battle in the past week that cost hedge funds and other short-sellers billions of dollars. Hargreaves, which runs a fund and has a trading platform with 1.5 million active clients, said it had benefited from strong volumes in the six months to Dec. 31 as people stuck at home during coronavirus lockdowns tried online trading. The company said the flood of younger people investing had reduced the average age of its clients to 37. The revenue from stockbroking commissions and advisory fees surged to 105.7 million pounds ($145.2 million) for the six months from 43.2 million pounds a year earlier. It said the main boost came from “client-driven equity dealing”. That helped push pretax profit up 10% to 188.4 million pounds, compared to 184 million pounds forecast by analysts. Hargreaves report a net addition of 84,000 clients, compared with 50,000 a year earlier, while assets under management rose to 120.6 billion pounds from 105.2 billion pounds. The company set its interim dividend at 11.9 pence, compared with 11.2 pence a year earlier. It raised its final dividend by 31% last year.