Hopes that the European Central Bank (ECB) may launch more pump-priming of the eurozone economy pushed London shares higher on Thursday.
Traders were set to comb the ECB's monthly policy announcement for hints about whether president Mario Draghi sees the need for further quantitative easing.
DailyFX currency strategist Ilya Spivak said: "With the Greece fiasco now on the backburner, traders will focus on the possibility that policymakers are mulling an expansion of stimulus efforts."
Reduced market tension over Greece also helped to lift Eurozone services activity in August back to the four-year high in June after a dip in July.
But the UK's service sector purchasing managers index fell to 55.6 last month from 57.4 previously, although any figure above 50 still denotes growth. Survey author Markit said it was the weakest rate of expansion in more than two years.
Markit economist Chris Williamson said: "As such, the UK economy looks set to grow by 0.5% in the third quarter, down from 0.7% in the three months to June, with the ongoing upturn almost entirely dependent on the service sector."
The FTSE 100 Index leapt 105.15 points to 6188 in early trading, helped not least by the fact that Chinese markets were closed for a bank holiday and World War II parade.
The Dow Jones closed nearly 300 points, 1.8%, higher at 16,351 while the S&P 500 similiarly added 1.8% to 1,948 and the Nasdaq gained 2.46% to 4,749.
In corporate news, bus and train operator Go-Ahead (LON:GOG) backtracked 194p to 2342p after it warned of a year-long delay in hitting bus profit targets.
Barclays (LON:BARC) gained 4.1p to 257.9p as the banking group agreed to sell its retail banking, wealth and investment management businesses and part of its corporate banking business in Portugal to Bankinter.
EasyJet (LON:EZJ) ascended 106p to 1778p after the budget carrier increased its profit forecast following a record August.
Elsewhere, antibiotics group Motif Bio (LON:MTFB) was 5.5p healthier at 66.25p as the U.S. Food and Drug Administration granted fast-track designation for iclaprim intravenous (IV) to treat acute bacterial skin and skin structure infections and hospital-acquired bacterial pneumonia.