The FTSE 100 <.FTSE> ended up 0.1 percent, while the mid cap FTSE 250 <.FTMC> index was held back with a 0.1 percent retreat due to the collapse of Indivior's shares (>> Indivior).

The drugmaker's shares sank 35 after it said it would appeal against a U.S. court ruling which potentially opens the way to a rival to the firm's Suboxone Film opiod addiction treatment.

"The company is facing a mammoth struggle now," said Neil Wilson, a senior market analyst at ETX capital.

Other midcaps suffered blows including Greene King (>> Greene King), down 3.8 percent after HSBC cut its rating on the stock and electronics retailer Dixons Carphone (>> Dixons Carphone), which lost 1.7 percent after both Investec and Morgan Stanley took a more negative view on its prospects.

Miners, which had already helped the FTSE stay in positive territory in the previous session, were up with Glencore (>> Glencore) rising 2.1 percent, Antofagasta (>> Antofagasta) 2.2 percent and Rio Tinto (>> Rio Tinto) 0.3 percent.

Energy sector heavyweights BP (>> BP) and Royal Dutch Shell fell 0.1 and 0.2 percent respectively.

Financials were mixed with HSBC (>> HSBC Holdings) and Lloyds (>> Lloyds Banking Group) falling slightly and Barclays (>> Barclays) and Standard Chartered (>> Standard Chartered) both up around 0.5 percent.

Provident Financial (>> Provident Financial), which made the headlines in August with a profit warning and the departure of its CEO Peter Crook, saw its shares fall 1.2 percent after Jeffries cut its recommendation from 'buy' to 'hold'.

(Reporting by Julien Ponthus; Editing by Richard Balmforth)

By Julien Ponthus