By William James, Huw Jones and Sinead Cruise LONDON (Reuters) -British finance minister Kwasi Kwarteng sought to reassure investment bank executives on Wednesday the government had sound fiscal plans, in the face of a meltdown in British assets. Kwarteng laid out a so-called mini-budget last Friday that sent British bond markets and the pound into a tail-spin, prompting the Bank of England to say it would buy as much government debt as needed to restore financial stability. In a meeting with finance industry bosses shortly before the central bank’s intervention, Britain’s new chancellor under…