Consumer confidence in the U.K. improved to its strongest level in five months in December, with further improvement expected going into 2020 amid optimism about the country's outlook post-Brexit, a survey by market research firm GfK showed.

GfK's consumer confidence index rose 3 points to negative 11 in December, matching its July reading.

The index tracking personal finances expectations for the year ahead increased 2 points to 3. Consumers' general economic outlook over the next 12 months improved as the relevant index rose 7 points to negative 27.

The major purchase index advanced to 3 from 0.

"Despite official warning signs about the flat-lining of Britain's economy, we know that record-high employment and below-target levels of inflation are helping to boost consumers' expectations for the year ahead," said Joe Staton, client strategy director at GfK.

Recent developments surrounding Brexit point to a rebound in consumer confidence next year, Staton added.

The latest GfK survey was conducted before the Dec. 12 U.K. general election, which gave the ruling Conservative Party its greatest parliamentary majority since 1987.