Mr. Niall Cody:

Because of the existence of marked gas oil, green here and red in Northern Ireland, diesel gets laundered and put into the supply chain. It was a really significant problem from 2012 on because there were changes to the system of sulphur content. The diesel was indistinguishable once laundered. The Office of the Comptroller and Auditor General did a report last year on mineral oil and the work Revenue has done there. There has been a significant legislative process that culminated in the introduction of the new marker in conjunction with Her Majesty's Revenue and Customs. The level of retail traders engaged in selling illegal diesel has reduced significantly. In 2016, we closed nine and in 2017 we closed four but around the middle of the decade, multiples of those figures were closed down. The proportion of the vehicle market in diesel has increased anyway, but we have examined the additional revenue as a result of our work on fuel laundering and it has been really successful. While I would not be complacent, the levels of sludge found and reported by local authorities, which was a very serious problem four or five years ago, have gone down significantly. We are very careful about that process.