The FTSE 100 benchmark index shot to its highest level since the day Lehman Brothers filed for bankruptcy last year.
The index jumped more than 1%, or 55 points, to 5,216.89 in early exchanges, as optimism over Wall Street's strong run last week spread.
The Dow Jones Industrial Average in New York finished up 78 points to 9,864.94 on Friday, climbing 4% over the week - the best performance since July.
Telecoms stocks, including Vodafone and satellite navigation group Immarsat, led the index higher.
Vodafone rose more than 3% after reporting its intention to move its shares listed on the New York Stock Exchange to the Nasdaq to cut listing fees.
Also in favour were Standard Chartered and Old Mutual both up more than 2%.
Miners accounted for some of the losers as profit taking continued after last's week's run.
Randgold Resources lost 0.6% to £46.12.
Meanwhile, investors seemed unfazed by an FT report that Barclays was planning to offload £4bn worth of complex credit assets to clean up its balance sheet.
Its shares were 0.3% lower at 375.85p at just after 10:00am.
Positive sentiment in the US also spilled over into Asia, with Tokyo's Nikkei powering above 10,000 for the first time in a week.
A weaker yen, which makes exporters more attractive to overseas consumers, helped the index add almost 2%, or 183.92 points, to finish at 10,016.39, its highest finish since 30 September.
