 After the outbreak of the Second World War Walpole remained in England , dividing his time between London and Keswick , and continuing to write with his usual <unk> . He completed a fifth novel in the Herries series and began work on a sixth . His health was undermined by diabetes . He <unk> himself at the opening of Keswick 's fund @-@ raising " War Weapons Week " in May 1941 , making a speech after taking part in a lengthy march , and died of a heart attack at Brackenburn , aged 57 . He is buried in St John 's churchyard in Keswick . 
