After losing his seat at Sleaford in the Liberal landslide of 1906, Chaplin was returned to the House of Commons at a by-election in May 1907 as member for Wimbledon. His opponent was the Independent Liberal candidate, Bertrand Russell, who stood on a platform of women's suffrage. Chaplin was opposed to this, saying "he might be very old-fashioned, but he drew the line at that". His own campaign focused on Tariff Reform and Imperial Preference, imperial union and opposition to Irish Home Rule. In his election address for the January 1910 general election, Chaplin supported the proposals of Lord Roberts and Lord Charles Beresford on national defence, and reiterated his support for Tariff Reform.