Kent Police have been granted extra time to investigate allegations of electoral fraud made against the Conservatives over the 2015 election for the constituency of South Thanet.
The investigation - one of several across the country - has the potential to develop into a full-blown expenses scandal for the Tories.
The allegations come from an investigation by Channel Four, which claims to have uncovered "compelling evidence" the Conservatives breached electoral rules.
Here's what you need to know about it:
- What are the claims?
The claims concern improperly reported election spending by the Tories during the 2015 election and in three by-elections in 2014.
The Tories are said to have kept certain costs out of local campaign budgets - if the expenses had been added in, it is alleged, the party would have breached strict electoral spending limits.
- What are these expenses?
The expenses relate to hotel stays, staff pay and the hire of coaches to ferry volunteer activists into marginal seats - a policy termed 'Battlebus 2015'.
- Why are these expenses problematic?
The Electoral Commission says that costs incurred for the promotion of an individual candidate need to be declared as part of local campaign expenses.
The Conservatives say Battlebus 2015 was a national campaign.
- So what's the problem exactly?
If the volunteer activists of Battlebus 2015 were campaigning on behalf of a specific candidate then a proportion of their costs should be declared as part of the local campaign.
According to Channel Four's investigation, if they had been, several Tory candidates would have breached their campaign spending limits.
- How much are we talking?
Channel Four estimates the amounts that should be attributed to local candidates would vary between an extra £2,000 and £2,500 depending on the region.
Campaign spending limits are dictated by the size of the electorate.
- Is it criminal?
Under election laws, it would be a criminal offence to knowingly make a false declaration.
- Is there anything else?
The waters are muddied slightly by the fact the Conservatives failed to declare accommodation costs for the activists, something the party has said was an administrative error.
It has already brought these to the Electoral Commission's attention.