Invoices obtained by Channel 4 appear to show that the Conservatives overspent on the Newark, Rochester & Strood and Clacton by-elections by around £100k. All three by-elections had defectors contesting the seat for UKIP.
The alleged overspends relate to hotel and hospitality costs for Conservative Party staff and activists working on the campaigns. Details have been passed on to the Police and the Electoral Commission.
Head over the the Channel 4 News website for the full detail.