BERLIN, Oct 5 - German firms with a presence in Britain or Northern Ireland must make provisions for the possibility of a 'very hard Brexit', the BDI industry association said on Thursday, adding it was concerned at progress in Britain's divorce talks with the EU. 'The British government is lacking a clear concept despite talking a lot,' BDI Managing Director Joachim Lang said. 'German companies with a presence in Britain and Northern Ireland must now make provisions for the serious case of a very hard exit. Anything else would be naive,' he said.