LONDON (Reuters) - Britain and the European Union have very different legal stances over the so-called Brexit bill London should pay as it leaves the bloc, Britain s Brexit minister David Davis said on Tuesday. After a third round of talks last week, officials said a gulf between the EU and Britain over how much London owes may be the biggest obstacle to a deal on an orderly Brexit in March 2019.  It is clear that the two sides have very different legal stances,  Davis told parliament during an update on the talks.  (EU chief negotiator) Michel Barnier and I agreed that we do not anticipate making incremental progress on the final shape of the financial deal in every round ... it is also clear there are significant differences to be bridged in this sector.  Davis also said it was still Britain s intention to negotiate a future trade agreement with the EU within the two-year divorce period. 