At closing, the benchmark FTSE 100 index was down 44.98 points, or 0.7%, at 6,371.18.
Aerospace firm Rolls-Royce led the downward trend, shedding 4.2% after media reports of an inquiry into the EU's airline maintenance market.
However, British Airways owner IAG rose 1.19% on a broker upgrade.
Mining giant Glencore began the session as the 100-share index's biggest gainer after it said it had started the sales process for two of its copper mines.
Shares in Glencore initially jumped 1.55% on the news that the mines, in Australia and Chile, were up for sale, but at close, they were down 6.2%.
Glencore is attempting to reduce $30bn (£19.5bn) of debt created by its 2013 takeover of Xstrata.
Against the dollar, the pound was 0.22% higher at $1.5350 and gained 0.19% against the euro to €1.3500.
(Close): London's leading shares dipped in Monday morning trading, indicating that an eight-day run of gains might be coming to an end.