John 'kneecaping' McDonnell did once hold economic and politics power. It was back in the 1980s at the GLC.
'Livingstone only averted financial catastrophe by sacking McDonnell in 1985. The former London Mayor revealed in his 1988 autobiography that McDonnell had 'exaggerated' spending figures to support his case that the GLC had to ignore the rates cap.'
Sounds perfect for the role of Labour Chancellor of the Exchequer. Certainly the BBC won't let the British public anywhere near learning about the past of John 'kneecaping' McDonnell.
That paragraph from http://www.dailymail.co.uk/news/article-3234679/So-far-Left-Red-Ken-sacked-ANDREW-PIERCE-explains-John-McDonnell-Livingstone-political-soulmates-bitter-fall-new-shadow-chancellor-s-spending-policies.html