By Barbara Kollmeyer, MarketWatch

MADRID (MarketWatch)--Gains swept through London's benchmark index on Friday after Scottish voters opted to stay in the U.K., with those moves in turn inspiring gains across Europe.

The FTSE 100 index rose 0.3% to close at 6,837.92. For the week, the London index logged a gain of 0.5%.

The FTSE 100 rose 0.6% on Thursday, bucking three straight sessions of losses. The result from the referendum that day showed 55% of Scottish residents voted to reject independence for their country. Scotland's First Minister Alex Salmond said after the defeat that he will step down as head of the Scottish government and resign as head of the Scottish National Party.

The British pound (GBPUSD) initially rallied when the first local results came out, but has later fallen back to trade at $1.6323, down from around $1.6400 when the polls closed on Thursday. Read: Scotland's 'No' vote: What strategists are saying

Scottish-linked stocks climb: Royal Bank of Scotland PLC (RBS) and Lloyds Banking Group PLC (LYG) stood out, rising 2.5% and 1.3%, respectively.

Among other Scottish firms, Standard Life PLC rose 1.4% and Weir Group PLC added 0.4%.

"Investors in these firms will be relieved that management will be able to devote their time to business performance, rather than fretting about contract changes or headquarters moves," said Brenda Kelly, chief strategist at IG, of those companies in a note ahead of the open.

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