Web traffic monitoring company Experian Hitwise claims that the web giant's marketshare has fallen to 89.33% in the territory, its lowest for five years.
Microsoft's Bing has made gains of late, claiming second place with 5% of the UK market. Yahoo's Ask is currently Britain's third choice search engine.
"In the UK, Bing has been using very aggressive tactics of promotion for the last few months in preparation for the Christmas season," Forrester Research analyst Luca Paderni told BBC News.
"But Google is still dominant, and we would need to see a trend over more months to call it a consistent decline."
Google is the number one search engine in numerous territories, but it plays second fiddle to Baidu in China and Yandex in the Russian market.