Diplomats posted to an Embassy or High Commission in the UK or who are in transit through the UK to their diplomatic posting are exempt from immigration control. This means that any checks are limited to verifying the person’s nationality and identity, that they are exempt from immigration control and they are the rightful holder of the document presented.
People holding diplomatic passports coming to the UK for any other reason are assessed against the Immigration Rules. In certain cases individuals are subject to international travel bans, imposed by the EU or UN. These are imposed for a number of factors and human rights violations and corruption could be a factor in this decision.