Financial stocks were the biggest drags on the blue chip FTSE 100 index, while consumer goods firm Reckitt Benckiser fell after naming PepsiCo executive Laxman Narasimhan to succeed outgoing chief executive officer Rakesh Kapoor.
The FTSE 100, up for seven days straight after falling more than 3% in a global stock market sell-off in May, dipped 0.3% while the mid-cap FTSE 250 was down 0.2% by 0745 GMT.
While last month's falls were driven by fears that President Donald Trump's spats with trade partners were set to weaken global growth, the rises since have seen markets convinced that the U.S. Federal Reserve and other central banks will respond quickly with stimulus if needed.
"The rally has paused and things may get a bit tricky now as we may well see the market start to think - one may even say realise - that the Fed is not necessarily going to ride to the rescue," Markets.com analyst Neil Wilson said.
Trump added to the trade nerves on Tuesday by saying he was not interested in a deal with Beijing unless it agreed to some "major points" in negotiations, while China declared it was "not afraid of fighting a trade war".
That spurred some weakness in exporters and other companies across the FTSE, with British American Tobacco falling 2.5% despite affirming its annual targets in what seemed to be a generally positive trading update.
Liberum analysts said the company's commentary on revenue from 'New Category' products, which includes vaping and e-cigeratte offerings, seemed to "suggest some softness".
Pendragon lost a quarter of its value and slumped to a more than six-year low, as it warned that significant declines in new car and used car registrations would lead it to report a pre-tax loss for the current year.
Online fashion group Boohoo, operating in a tough retail market that saw hits to fashion retailer Ted Baker and fast fashion chain Quiz Plc on Tuesday, slipped 3% despite posting robust quarterly sales growth.
Traders said the move may have been spurred by a small contraction in the company's gross margin for the quarter.