The Conservative Party has been fined £70,000 after an Electoral Commission probe into election expenses prompted by the reporting of Channel 4 News.

The independent elections watchdog said the party had made “numerous failures” in reporting its expenses for the 2015 General Election and three by-elections in 2014.

Commission chairman Sir John Holmes said the Tories’ failure to follow the rules “undermined voters’ confidence in our democratic processes” and said there was a risk political parties were seeing such fines as “a cost of doing business”.