None. As a former UK diplomat, Parvez Khan is not subject to the EU revolving door rules.
"As lead attaché on securities and markets, Parvez led negotiations for the UK in the European Council on highly political and technically complex regulatory issues. Some of the high profile issues Parvez has dealt with were legislative initiatives on hedge funds and private equity, short selling, derivatives and markets infrastructure. Parvez was also involved with the development of the new European Supervisory Authorities". (Source: G+ website)
“Parvez has second-to-none understanding and experience of financial services regulation and decision-making. With the amount of legislation in the that field currently in the pipeline, we are very happy that he will be helping us strengthen our offer to clients in that sector”. (Source: European Agenda)
Update July 2015: Parvez Khan now works for Avisa Partners lobby consultancy as a "consultant dedicated to financial regulation and trade issues".
"Mr Khan used to work for the UK Financial Services Authority which is responsible for the regulation of UK banks. He also worked for the UK government on finance issues in Brussels. But he is now working for a Brussels lobby consultancy, one of whose major clients is RBS - the Royal Bank of Scotland. This should provoke significant questions about conflicts of interest which might arise. As a former UK diplomat, Parvez Khan is not subject to the EU revolving door rules".