(Reuters) - Britain's FTSE 100 advanced further on Monday as investors were hopeful of some progress to end the prolonged U.S.-China trade war and luxury brand Burberry gained after French peer LVMH agreed to buy U.S. jeweller Tiffany.The FTSE 100 added 0.7% with miners and Asia-focused HSBC providing the biggest boost, after U.S. national security adviser Robert O'Brien said an initial trade deal was still possible by the end of the year.The index, which had jumped more than 1% in the..