The FTSE 100 <.FTSE> closed down 0.06 percent at 7,533.81 points with financials and materials firms being the biggest drags on the index.
Investors expect the leading share index to stall into the year-end, with economic and political worries and a stronger pound preventing further gains.
"I would sit on the fence with it. The FTSE has moved a long way already and it looks quite toppy," said Rory McPherson, head of investment strategy at Psigma Investment Management. The index is up 5.5 percent year-to-date.
"The economic data has been almost universally poor. It's not a brilliant picture which you would associate with the FTSE doing well," he added.
Mondi (>> Mondi) was the main weak spot on the index, down 7.6 percent after the paper and packaging manufacturer said full-year results would be "modestly below market expectations" due to cost pressures and negative currency moves.
Among the mid-caps, embattled sub-prime lender Provident Financial (>> Provident Financial) fell 4.3 percent after Barclays cut the stock to "underweight".
"We are cautious on the shares given our lack of confidence for a turnaround of the home credit business and the unquantifiable size of potential FCA (Financial Conduct Authority) redress," said Barclays' analysts in a note, referring to the UK regulator's powers to demand remediation payments from the company to consumers.
Another stressed midcap was British recruitment company PageGroup (>> PageGroup), which lost 9.2% amid uncertainty over Brexit hitting the recruitment market.
"Strong growth in most regions was partly offset by continued weakness in the UK," said Liberum analysts.
Some positive corporate news lifted a number of stocks such as homeware retailer Dunelm (>> Dunelm Group plc), which jumped 5.4 percent after it reported first-quarter revenue rose nearly 25 percent as better weather drew more customers.
Medical devices company Smith & Nephew (>> Smith & Nephew), was up 3.1 percent after a report that activist investor Elliott built a stake in the company.
(Reporting by Helen Reid and Julien Ponthus; Editing by Jon Boyle and Toby Davis)
By Helen Reid