26/05/2016 09:37 BST | Updated 26/05/2017 06:12 BST

The Next Expenses Scandal?

Did parties systematically spend more money than permitted in the 2015 general election campaign? Can money now determine the outcome of an election in the UK? If we don't act now we may never really know. We have less than two weeks to ensure that the police take action on expenses - on 11 June the legal deadline for prosecutions will pass.

Election expenses can sound like a very technical topic but they are fundamental to ensuring that we have free and fair elections. Elections are an expensive business for political parties. Together the UK's six largest parties spent £39m on the 2015 general election campaign, an increase on the £34.4m spent in 2010.

With so much money involved, spending limits play a vital role in keeping elections fair. The rules around election expenses are there to ensure a level playing field for candidates. If politicians can get around the rules, it could be money that makes the difference in marginal seats where the election is decided by a few hundred votes.

Channel 4 News have set out some very clear questions that have to be answered about the way in which some spending was reported as well as highlighting some expenditure that appears to not have been reported at all. What we need now is action from the police.

There are allegations that at least 29 current MPs broke campaign spending limits. Police forces across the country are now responding to these allegations. 11 police forces are already investigating election expenses, but some forces - like Avon & Somerset - are refusing to take action before the 5 June deadline. The Conservative Party have now gone to court to stop Kent Police from extending their investigation into election expenses in South Thanet.

Separate investigations are a waste of public money. Only a national investigation can determine whether there were systematic breaches of the rules rather than the oft-claimed 'administrative error'. The Metropolitan Police should coordinate investigations into election expenses allegations nationwide.

But this is about more than just individual wrongdoing by MPs. We need to fix the system by making election spending returns transparent. Channel 4 News have done a brilliant job of bringing election expenses allegations to light. The lack of transparency around expenses means that only the most committed researchers have the time and resources to investigate suspected breaches. Election spending returns are not available in full online, only to those who make the trek to the office of their local council. In contrast, donations to political parties are available in online, searchable databases for all to see on the Electoral Commission's website.

The Electoral Commission should also have the power to investigate local candidate spending allegations. The Commission has called for these powers repeatedly since 2013 but the government has yet to respond. Much of our electoral law is quite literally Victorian, which makes investigating and prosecuting breaches of the rules much harder than it needs to be. For the public to have faith in the conduct of our elections there must be a clear line of accountability. Voters need to be confident that all allegations will be investigated. There shouldn't be a postcode lottery on police investigations.

This is how an unnamed Conservative MP reportedly responded to the allegations:

"Everyone knows that election expenses are a work of can drive a coach and horses through the loopholes."

We have less than two weeks to see if he is right. Will there be consequences for flouting election laws? We have just launched a petition calling for a national police investigation into election expenses, which you can sign here.