The problem is, hundreds of people are giddily opening their mail and immediately sharing a picture of their ballot online.

It took BuzzFeed News five minutes searching on Twitter and Instagram to take control of multiple votes in the Labour leadership election, gaining full access to the party's online voting system and potentially depriving Labour supporters of the right to back their preferred candidate.

It also gives strangers the ability to steal a vote in the deputy leadership election, plus the Labour mayoral nomination if they live in London.

This is the latest issue to hit the leadership vote, which has already been hit by accusations of entryism by the far-left, along with concerns that there has not been sufficient vetting of individuals attempting to infiltrate the system from rival parties, while one MP has said a legal challenge to the result is almost inevitable. As a result thousands of people have already been banned from voting by the Labour party.