The FTSE 100 <.FTSE> was down 1.44 percent, its worst day since October 11, as a survey showed uncertainty about Brexit left the economy at risk of contracting.

Data also showed euro zone business growth was at its weakest pace in over two years while unsettling signs in the U.S. bond market had triggered a sharp fall in Wall Street on Tuesday.

Asthead <.AHT>, which derives the majority of its revenues in the U.S. was the worst performer among British blue chips, down 5.8 percent as investors worry U.S. yield curves could be signalling an impending recession.

Shares in UK housebuilders however bounced off two-year lows as investors and traders covered bearish bets ahead of next week's vote on Prime Minister Theresa May's Brexit deal.

FTSE 100 housebuilders Persimmon, Berkeley, Barratt Development and Taylor Wimpey were the best performing stocks, up 7 percent, 6 percent, 5.1 percent and 4.2 percent respectively.

On Tuesday, May suffered embarrassing defeats at the start of five days of debate that will lead to a parliamentary vote on Dec. 11 on her proposed agreement.

After a European Court of Justice opinion on Tuesday that Britain could unilaterally revoke Brexit if it wanted, JPMorgan said it now reckons the chances of Britain remaining in the bloc have increased to 40 percent from 20 previously.

Still, companies continue to prepare for the possibility of no deal.

Fashion retailer Joules Group Plc said on Wednesday it would set up a distribution facility in the EU and bring inventory of its 2019 spring-summer collection into the UK earlier than usual as part of its contingency plan.

Hargreaves Lansdown, down 4.4 percent, was on track for its worst day since Oct. 11 after Morgan Stanley cut the stock to underweight, noting that a weaker UK economic outlook is likely to hit 2019 flows, and weaker stockbroking fees, among other pressures.

"We see several new headwinds on the horizon which could derail the long-term growth story and trigger share price underperformance," the analysts said.

Among other gainers, biotech company Shire was up 3.1 percent after Takeda Pharmaceutical shareholders approved a $59 billion takeover of the London-listed company, the biggest overseas acquisition by a Japanese company.

On the FTSE 250, embattled travel operator Thomas Cook rose 51.4 percent on hopes it would not need to issue new equity.

(Reporting by Josephine Mason and Helen Reid, editing by Matthew Mpoke Bigg)

By Josephine Mason and Helen Reid