(For a Reuters live blog on U.S., UK and European stock markets, click LIVE/ or type LIVE/ in a news window) * FTSE 100 up 0.1%, FTSE 250 adds 0.7% July 22 (Reuters) - British stocks rose on Thursday as a set of positive corporate results helped outweigh concerns over increasing COVID-19 cases, while Unilever was the worst blue-chip performer after it cut its full-year margin forecasts. The blue-chip FTSE 100 index inched 0.1% higher, led by travel, retail, and banking stocks. Unilever Plc dropped 4% after it reduced annual operating margin forecast while reporting higher-than-expected underlying sales growth for the second quarter. The domestically focussed mid-cap index rose 0.7%, with Howden Joinery Group and IG Group being the top boost to the index on positive results. Transport firm FirstGroup jumped 3.1% after it increased its planned shareholder returns by 135 million pounds ($185.29 million) after closing the sale of its U.S. bus assets to private equity firm EQT Infrastructure. (Reporting by Shashank Nayar in Bengaluru; editing by Uttaresh.V) Our Standards: The Thomson Reuters Trust Principles.