In 2016 Denis travelled to the high Arctic with a team of explorers who walked to the North Pole to highlight global warming and the receding ice cap. In 2018 he published his huge homage to David Bowie, the limited edition boxed set "Ricochet : David Bowie 1983", which covers their first world tour together, and includes five books, limited edition vinyl, and three limited edition prints with certificates. It is the first official Bowie product since David's passing to feature the official David Bowie estate stamp, designed by Jonathan Barnbrook, and based on the design of an 'ex libris' stamp that David attached to his private book collection.