Install a temporary government until the last election is proved legitimate.

If it is proven that the present government is not legitimately in place, it may call into question whether its actions in governance can be legally upheld. Under the circumstances an alternative should be sought, to ensure that the business of government complies with UK and International law.

It's not clear how a temporary government would be chosen, or who would be eligible to be a member of that government.

It's also not clear who would have the authority to install such a government. We can only accept petitions about matters that the Government or Parliament are responsible for. The Prime Minister of the UK - who chooses the members of a government - is not chosen by the UK Government or Parliament. After a general election, the Queen decides who to invite to form a Government. In practice, this is usually the leader of the political party that wins the most seats in a general election. You can find out more about this here:

http://www.royal.gov.uk/MonarchUK/QueenandGovernment/QueenandPrimeMinister.aspx