The FTSE 100 <.FTSE> ended 0.1 percent up, as European markets edged higher ahead of a widely expected rate hike from the U.S. Federal Reserve later on Wednesday.
Boohoo shares jumped 11 percent after the fashion retailer raised its full-year sales forecast and first half profit increased 22 percent.
Miners Randgold Resources and Fresnillo were among the leading FTSE losers, both down 2.5 and 3.6 percent respectively, while oil majors Shell and BP also lost ground.
Mid-cap Indivior declined 16 percent after the drugmaker revised its full-year earnings guidance as it sharply lowered its revenue expectation for opioid addiction drug Sublocade.
AA fell 13 percent after the roadside recovery and insurance group said extreme weather had raised its costs and hit first-half core profit.
Concerns about the progress of Brexit negotiations dogged sentiment with British carmakers triggering some contingency plans by certifying models in Europe.
British stocks, however, remained supported among value-hunters because of their relatively cheap valuations compared to other major equity markets.
At around 4 percent, Britain offers a higher dividend yield than markets such as Europe and the United States.
On a valuation basis, the 12-month forward price-earnings multiple is 13 percent below global equities while the price-to-book ratio for the index is about a fifth below its long term average, according to Thomson Reuters data.
"These valuations chime with positioning data that show the UK to be somewhat of a consensus underweight," said Mark Richards, a global multi-asset strategist at JP Morgan Asset Management in London.
As few as 630 UK-based finance jobs have been shifted or created overseas with just six months to go before Brexit, a far lower total than banks said could move after Britain's surprise 2016 vote to leave the European Union, according to a Reuters survey.
(Reporting by Saikat Chatterjee; Editing by Mark Heinrich)