The FTSE 100 was 0.1 percent lower at 0939 GMT, on track for its third straight session of losses and its worst weekly performance since early December.
The FTSE 250, more domestically focussed, edged higher by 0.1 percent, buoyed by financial stocks that were led by a bounce in Metro Bank after its shares crashed in the previous session.
At the bottom of the main index, Vodafone was down 2.7 percent at its lowest since November after its South African unit reported a slowdown in service revenue growth. It was the biggest drag on the blue chips.
Heavyweight oil stocks also fell 0.4 percent due to lower crude prices on lingering concerns about slowing global economic growth. The dip put the index on track for its steepest weekly fall since October last year.
Broader sentiment continued to outweigh Brexit uncertainties. The European Parliament's Brexit group said it would not approve a Brexit deal that did not contain a full "backstop" provision to avoid a hard Irish border.
European companies have been stockpiling inventories and setting up units outside of the UK ahead of Brexit. The latest jolt came from Airbus, who warned it could shift future wing-building out of Britain in the absence of a smooth exit from the European Union.
Despite a looming March 29 deadline, there is very little clarity on how Britain's exit from the EU would pan out after Prime Minister Theresa May's deal suffered a massive defeat in the parliament this month.
Sterling notched a 10-week high in the previous session as investors pinned their hopes on British lawmakers preventing a no-deal departure.
"In terms of Brexit, neither the pound nor the FTSE are doing much this morning. I think again it's a lot of hot air right now without much progress," said Spreadex analyst Connor Campbell.
Gary Waite, portfolio manager at Walker Crips Investment Management, said with various permutations surrounding Brexit, it is "really impossible to say with any certainty what road we're going to go down."
Rentokil was also among big fallers, sliding 2 percent after US peer Rollins' results missed Wall Street expectations.
Consumer goods maker Reckitt Benckiser fell 2.3 percent to a more than six-month low as Jefferies downgraded the stock in the wake of the departure of its longstanding CEO.
Outperforming the index was wealth manager St James's Place , which climbed 2 percent after beating forecasts for net inflows of client cash in a tough fourth quarter for global markets.
Equipment rental company Ashtead also added nearly 2 percent after NYSE-listed rival United Rentals' upbeat results.
Earnings also impacted midcap shares. Frankie & Benny's owner Restaurant Group was the top faller, down 5.5 percent after predicting lower full-year like-for-like sales.
Among other moves, Just Eat added 3.4 percent after a JP Morgan upgrade while homebuilder Crest Nicholson shed 1.7 percent, with a trader citing a rating downgrade.
Trading platform CMC Markets rose 1.7 percent after it said the Sino-US trade tensions boosted client activity on its online trade platform in the third quarter.
Among small-caps, NCC Group fell 20 percent to its lowest since May 2017, after it guided to lower full-year EBIT and said sales in the UK were held back by softer demand.
AIM-listed tonic water maker Fevertree jumped 10 percent and was on track for its best day in more than 3 months after guiding to an almost 40 percent surge in full-year revenue.