During Harcourt's era, death duties for estates worth £1 million or more were set at a modest 8 percent. However, this tax became a reliable income source and gained popularity among the majority who weren't subject to it. As a result, taxes were progressively increased, reaching an astonishing 60 percent by the time World War II began, drastically affecting even the wealthiest individuals.

In addition to heightened death duties, income taxes faced continuous hikes alongside the introduction of new taxes like the Undeveloped Land Duty and Incremental Value Duty. These measures disproportionately impacted those wealthy landowners, contributing to an increasingly burdensome tax system that targeted the affluent and their estates.