In 1979, the UK had a Zero Rate, a Basic Rate of 12.5% charged on "luxury" items and a reduced rate of 8% charged on most other goods and services.
When the Conservatives came to power that year, Chancellor Geoffrey Howe increased both of these to a single rate of 15%, to partially offset the impact of large cuts to the Basic and Higher Rates of Income Tax. This was portrayed as a deliberate move aimed at shifting the burden of taxation from earnings to consumption.
VAT remained at 15% until 1991, when Norman Lamont increased it to 17.5%.