Why is UK business optimism at its weakest in over four years?

Optimism among UK companies has dipped to its lowest in over four years. This is according to the latest Markit Business Outlook survey. Furthermore, worldwide business confidence fell to its lowest level in over six years due to growing political uncertainty, enhancing worries of the potential impact of Brexit on the UK economy. Chris Williamson, IHS Markit's chief economist, spoke to Simon to discuss the survey in more detail.