Denis is currently working on
Research into British and British Imperial History of the 19th and 20th centuries.
His best selling book Empire: the British Imperial Experience From 1765 to the Present was published in 2011 in a revised paperback edition.
The life and work of Alison Uttley. Manchester University Press has recently published in paperback a 3rd edition of his authorised biography. A paperback edition of The Private Diaries of Alison Uttley was published in the Spring of 2011.
His biography of George VI was published in paperback in 2012 to mark the 60th anniversary of the monarch's death.
In the spring of 2013 a new paperback edition of The Boer War (co-authored with Dr. Keith Surridge) was published.
In 2014 his biography of Lord Reading was published in paperback.
His two novels, The Adventures of Long John Silver and Return to Treasure Island are being translated into Russian for hardback and paperback editions, to be published in 2015.
Also in 2015 his book Balfour and the British Empire was published in paperback, as was his biography of Palmerston.