The FTSE 100 was up in early trading, rising 0.4 per cent to break through the important 5,900 barrier, with some of the main share price moves driven by regulatory investigations.
Rolls-Royce fell heavily after admitting that it was co-operating with the Serious Fraud Office on a probe into potential corruption and bribery at its Asian intermediaries.
The company warned that outcomes "could include the prosecution of individuals and of the company" and investors took flight, driving the share price down 2.7 per cent to £8.89.
On the flipside, Standard Chartered rose as shareholders were pleased by reports that the firm will pay $330m to settle a dispute over its alleged dealings with Iran. Shares were up 2.3 per cent.
But stoic HSBC investors were non-plussed by reports that the bank may have to pay a $1.8bn fine over money-laundering lapses, with the share price largely unchanged.
Elsewhere investors waited for the final Bank of England and European Central Bank monetary policy decisions of the year.
There was also renewed hope that politicians in Washington DC can avoid the so-called "fiscal cliff" of year-end tax hikes and spending cuts after President Obama said a deal was possible within a week. His comments boosted stocks on Wall Street and in Asia.
In London miners led the upwards charge, with Antofagasta topping the leaderboard with a 3.1 per cent increase. Vedanta and Evraz were closed behind. The entire resources sector has been boosted this week by encouraging news from China about an attempt to stimulate growth in the fast-growing economy.
Defensive stocks fell back, while accountancy software firm Sage continued yesterday's downward slide.
In the FTSE 250 retailer Dixons was up five per cent, while JD Sports fell 4.6 per cent.
In Asia the Nikkei was up 0.8 per cent and the Hang Seng down 0.1 per cent.