Despite a positive start, Britain's FTSE 100 <.FTSE> ended the session down 0.65 percent, roughly in line with European peers and as most sectors traded in negative territory.

"When you consider how much ground the FTSE 100, DAX and CAC have made in the past couple of months, a pullback of this size isn’t anything out of the ordinary," David Madden, market analyst at CMC Markets, said.

Shares in the world's largest security group G4S (>> G4S) sank 4.7 percent after the firm downgraded its revenue outlook for the rest of the year.

"The main drag is the Middle East and India region. Excluding these, G4S would have achieved 6.1 percent organic growth," said Stifel analysts.

Associated British Foods (>> Associated British Foods), which owns the Primark fashion chain as well as major grocery and agriculture businesses, fell 3.6 percent after the CEO said sugar profits would fall in 2017-2018 due to lower EU prices.

The mood in the retail sector was also depressed after the British Retail Consortium (BRC) said shoppers cut back their spending last month at the fastest pace for any October since 2008.

"This is a concern ahead of a key trading period," HSBC analysts commented.

Energy stocks provided some support as crude prices held around mid-2015 highs with BP (>> BP) rising 0.7 percent and, in the mid-cap segment, Tullow Oil (>> Tullow Oil) up 3 percent.

William Hill (>> William Hill) shares jumped 4.3 percent after Bank of America Merrill Lynch analysts gave the gambling company a double upgrade to "buy" from "underperform".

William Hill and rival betting firm Ladbrokes Coral (>> Ladbrokes Coral Group) had made gains last week after the UK government's review on maximum stakes for gambling machines, with analysts saying the risk was priced in.

Bank of America Merrill Lynch analysts wrote on Tuesday: "Even in a worst case scenario of a 2 pound cap on fixed odds betting terminal machines, William Hill would offer an attractive value opportunity."

Among small-caps, Fevertree (>> Fevertree Drinks PLC) sparkled, up 14.9 percent after an impressive trading update. The maker of premium mixers said 2017 results would beat expectations.

(Reporting by Helen Reid and Julien Ponthus; editing by Ralph Boulton and Adrian Croft)

By Helen Reid and Julien Ponthus