By Sara Sjolin, MarketWatch

LONDON (MarketWatch) -- U.K. stocks made solid gains on Friday, with the FTSE 100 index rounding off its best week since February, after the Bank of Japan took investors by surprise and announced more stimulus measures for the stumbling Japanese economy.

The London benchmark climbed 1.3% to close at 6,546.47, ending the week 2.5% higher. That marked the strongest weekly advance since the week ended Feb. 21, according to FactSet.

The trading optimism followed an upbeat mood in Asia, where Japan's Nikkei 225 index surged 4.8% after the country's central bank voted to expand the pace of its quantitative easing. The yen (USDJPY) tanked on the news, with the dollar touching its highest level against the Japanese currency since 2008.

In the U.K., shares of Royal Bank of Scotland Group PLC (RBS) added 6.2% after the lender said it swung to a profit in the third quarter. It also said it would set aside GBP400 million ($640 million) to cover foreign-exchange probes.

British Airways parent International Consolidated Airlines Group SA (ICAGY), picked up 4.7% after raising its full-year earnings guidance, with a turnaround at its Spanish unit Iberia spurring a 30% rise in operating profit in the third quarter.

On a more downbeat note, shares of Randgold Resources Ltd. dropped 2.7% as gold prices continued to slump.

You're invited: A free evening event focusing on investing opportunities in Europe

Will you be in London on Dec. 3? Then you are invited to our MarketWatch Investing Insights event, "The worse Europe gets, the more you should invest"

Governments are in trouble, reform efforts have stalled, unemployment is climbing... the news from the eurozone is bleak. And investors are fleeing. But that's a mistake: The worse the economic data from Europe get, the more you should be buying. Why? Because actions by the ECB will boost asset prices and the stock market in particular. And, big exporters can grow sales. Lower costs and steady sales translate into higher profits and dividends. Join us for an evening of cocktails and conversation to explore these opportunities.

Our panel will be led by MarketWatch Columnist Matthew Lynn, a renowned financial journalist based in London and the author of "Bust: Greece, the Euro and the Sovereign Debt Crisis." He'll be joined by Mark Hulbert, MarketWatch columnist and editor of the Hulbert Financial Digest. This event is free, but RSVPs are required. It will be held Wednesday evening, Dec. 3, in London. For more information or to RSVP, send an email to marketwatchevent@wsj.com

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