Whenever you appoint a new director and send the relevant paperwork to Companies House, it will automatically check that individual details against the Register of Disqualified Directors.
From 8 June 2014 a similar procedure will be introduced for undischarged Bankrupts (and other types of personal insolvency that prevent an individual acting as a director).
Source: http://www.companieshouse.gov.uk/pressDesk/news/undischargedBankruptsProjects.shtml