B ritain's top share index advanced for a fourth straight session to set a new seven-week high on Thursday, with encouraging reports from companies such as BSkyB and Lloyds improving sentiment, Reuters reported. British pay-TV operator BSkyB climbed 3.9 percent, the biggest gainer on the blue-chip FTSE 100 index, after saying it added 74,000 net new TV customers in its third quarter, more than double the growth it recorded last year. The FTSE 100 index was up 0.2 percent at 6,791.12 points by 0708 GMT after setting a seven-week high of 6,796.58 points earlier in the session. The index is less than 2 percent away from a life-time high set in May 2013. Trading volumes are likely to be thin as most of other stock markets in Europe are closed for the May Day holiday.