US law firms continue to drive a fierce salary war in London, leaving UK firms scrambling to keep up with soaring pay for junior lawyers, but as starting salaries rise, growing pay gaps threaten to unsettle senior associates, writes Maria Ward-Brennan. As of next month, London associates at Quinn Emanuel will see their salaries increase by 5 per cent across the board, with newly qualified (NQ) lawyers set to take home £189,000, up from £180,000.…