 Complete the following phrase:  In April 2016, Mayor of London and Conservative MP Boris Johnson was accused of dog whistle racism by Shadow Chancellor of the Exchequer and Labour MP John McDonnell when Johnson suggested U.S. President Barack Obama held a grudge against the United Kingdom due to his ancestral dislike of the British Empire as a result of his part-Kenyan heritage, after Obama expressed his support for the UK to vote to remain in the European Union ahead of the 