LONDON (Reuters) - Many international banks and financial services firms based in Britain will decide in the first quarter of next year whether to move operations away from Britain ahead of Brexit, a senior official at Britain s finance ministry said on Wednesday. Katharine Braddick, the ministry s director general for financial services, said banks using Britain to serve clients in the European Union were showing the most urgency in considering relocation plans.  Those plans, if you like, harden, become more firm, at the point at which they start to alter contractual paperwork. For most of the firms that we talk to that will fall at some point in the first quarter of next year,  Braddick told lawmakers.  
Early 2018 is crunch time for banks' Brexit decisions: UK official