The political cost of Conservatives' record fine - BBC News
The Tories aren't the only party to have messed up their election expenses but it could cause them significant political pain
David Cameron gets on the Conservatives' 2015 election battlebus

Money and politics. Put them together and the mix can be toxic.

After long running investigations and digging by Channel 4 News and the Daily Mirror, rumblings over how the Conservative Party used cash in the General Election campaign in 2016 have burst into the open with a record fine from the Electoral Commission.

Seventy thousand pounds is a lot of money, but in the context of a political campaign where millions of pounds are spent, it's not exactly going to break the Tories' bank. But the political cost of what MIGHT happen next is much higher.

Thirteen police forces are now looking at whether the mistakes made might constitute criminal offences. If that was to happen, there could be by-elections in seats around the country, that could seriously affect the PM's unhealthily slim majority in Parliament.

And the whiff of financial wrong-doing is an odour no political party wants. But how likely is that actually to happen?

On the central charge laid at the Tories' door - were they deliberately trying to channel national cash into local campaigns to get round the spending rules, the Electoral Commission report is not completely conclusive.

They've found no direct evidence of intent to fiddle the system, but the message is essentially, that the party should have known better.

Senior Tory sources tell me they think it's unlikely the mistakes, and there were plenty of them, will reach the hurdle for the prosecution. The CPS has to believe there is a good chance of a successful conviction, and while this is speculation, senior Tories don't believe in most of the cases that's likely.

When it comes to South Thanet however, the seat where the Conservatives were desperate to hold off Nigel Farage, Tory insiders fear the situation may be more fraught for them.

The discrepancies may be more serious, the amounts of money more significant, and therefore, potentially, this could bring a lot more trouble in the coming months.

The Tories aren't the only party to have messed up their election expenses, both Labour and the Liberal Democrats have also been fined. But it's most serious for the Tories and could, hypothetically, cause a significant amount of political pain.