Death & the Jubilee - David Dickinson

It is now 1897 and London is preparing for Victoria's Diamond Jubilee, celebrating her sixtieth year as Queen and Empress of a quarter of the surface of the globe. Fifty thousand troops from across the Empire will gather in the capital and over a million loyal subjects will watch Her Majesty ride in state from Buckingham Palace to St Paul's Cathedral. The immensity of the occasion brings danger.
When a body is found floating in the Thames, Lord Francis Powerscourt is called in. His researches lead him to a mysterious mansion in Oxfordshire, where a second corpse is found, burnt to death, the door of the victim's room locked from the outside. Following these deaths by water and fire, Powerscourt realizes that the stakes are far greater than he imagined - in his hands lies either the success or failure of the Imperial Jubilee.