By Simon Jack
By Theo Leggett
Business correspondent, BBC News
Finally, motorists in Birmingham and Sheffield have been confronted by a BBC reporter who secretly filmed them buying red diesel to use in their own cars.
It's illegal for regular drivers to use the fuel, which is about 50p cheaper than a litre of normal diesel.
HM Revenue and Customs estimates that the crime costs the UK £100m a year in lost tax revenue.
Red diesel is intended for use by farmers and construction workers in tractors and diggers.
By Roger Harrabin
BBC environment analyst
By Anthony Reuben
BBC Reality Check
Some 120,000 people have marched in high-visibility yellow vests to protest a price rise in diesel.
Reporter, BBC Radio Guernsey
There have been no changes to Guernsey's 2019 budget yet, despite it facing more than 40 amendments.
It was a day dominated by petrol and diesel.
Two of Deputy Jennifer Merrett's amendments were thrown out regarding withdrawal rates then Deputy Gavin St Pier found himself apologising after his committee had failed to discharge its duty on finding alternative ways of taxing motorists - proposals that will now have to be found by September 2019.Copyright: Getty Images
The biggest news on the opening day of debate was fuel duty, which is going up despite two amendments being placed to prevent a price hike.
That means the tax on fuel will remain at its new level of 70.1p per litre.