The FTSE 100 followed global equities into the red as markets in the US and Asia suffered growing weakness.
The blue-chip index was 0.4% lower at 7,458, rounding off a disappointing week for equities.
Utilities were among the fallers with British Gas owner Centrica (CNA) and SSE (SSE) dimming by up to 1.5% each.
On Wall Street, the S&P 500 dipped 1.8 points to 2,821 overnight, while Japan's Nikkei 225 reversed 0.9% to 23,274 this morning.
Back in the UK, construction output growth was on the verge of vanishing as the Purchasing Managers' Index fell from 52.2 in December to 50.2 in January. A reading of over 50 implies growth and one under 50 suggests contraction.
Brent crude oil ticked 0.2% lower to $69.47 per barrel.
MID AND LARGE CAP RISERS AND FALLERS
Cineworld's (CINE) acquisition of US cinema chain Regal was approved, alongside the rights issue to fund the deal. The stock advanced 0.4% to 514p.
Challenging market conditions at broadband provider BT's (BT.A) global services division hit its third quarter sales, down 3% to £5.97bn. Shares in BT reversed 5.1% to 242.9p.
AstraZeneca (AZN) missed analysts' earnings per share (EPS) forecasts of $3.61. The pharma giant said EPS is expected to hit $3.30 to $3.50 in the year to 31 December 2018. Despite this, the pharma giant was flat at £48.89.
Wood Group (WG.) announced US tax changes will provide a non-cash credit to the profit and loss account in the year to December and push the firm's tax rate in the future. The stock gained 1.6% to 660.2p.
A negative outlook from broker Jefferies on estate agent disruptor Purplebricks (PURP) triggered a 4.7% slide in the stock to 431.6p. Purplebricks responded to Jefferies' criticism of its revenue recognition policy, claiming full year trading is in line with expectations.
Home credit business Provident Financial (PFG) appointed Malcolm Le May as chief executive officer, nearly six months after the departure of Peter Crook. Shares in the firm rose 5.8% to 708.8p.
SMALL CAP RISERS AND FALLERS
Laura Ashley (ALY) was marked 1.8% lower to 6.1p after taking back brand licensing rights to Japan, Taiwan and Hong Kong from Aeon.
A positive update on Eurasia Mining's (EUA) mining permit application for the Kola Peninsula in Russia sparked a 28.4% share price rally to 0.3p.
Mobile Streams (MOS) warned that first half revenue would more than halve thanks to challenging market conditions in India. Over a third of the company's value was wiped off.