The Square Mile tracked progress across the Atlantic as the FTSE 100 Index climbed 47.5 points to 6822.8 while Germany's Dax and France's Cac 40 were also ahead.
In New York, the S&P 500 had broken through the 2,000 barrier for the first time yesterday with confidence boosted by the improved outlook.
The latest session also saw Wall Street higher, buoyed by corporate deals involving Burger King and Amazon as well as US data showing a surge in orders for manufactured goods and consumer confidence at a seven-year high. Trading volumes were light, with progress likely to be tested later in the week by publication of the second estimate of the US GDP figures on Thursday.
On currency markets, sterling was little changed at just under 1.66 US dollars and a little below 1.26 euros.
But the pound's recent strength was a factor in corporate updates as it has caused a headache for UK-listed firms with overseas earnings.
This was highlighted by cleaning and household supplies firm Bunzl and advertising and marketing giant WPP, although shares in the FTSE 100 pair were still higher despite the impact on half-year results.
Bunzl, which supports businesses worldwide by supplying items such as carrier bags and other packaging, reported a two per cent rise in profits to £132.3m.
Shares were 9p stronger at 1639p, leaving the FTSE 100 stock up 13 per cent since the start of the year.
There was a larger gain in the session for WPP, which climbed 17p to 1244p after reporting a 1.5 per cent rise in profits to £532m as it grew business in the UK and US to offset weaker trading in continental Europe. The company, led by founder and chief executive Sir Martin Sorrell, highlighted a range of uncertainties such as a fragile eurozone and unstable Middle East. But shares rose after it said July net sales were up 2.8 per cent on a like-for-like basis, against a strong comparative growth rate in 2013 of 4.1 per cent.
Elsewhere on the FTSE 100 risers board, Associated British Foods rose 59p to 2871p after analysts at JP Morgan Cazenove said they expected the fashion chain to double profits over five years.
Airline stocks were climbing with British Airways firm International Airlines Group lifting more than three per cent, or 12.1p, to 358.1p while easyJet rose nearly three per cent, or 35p, to 1354p.
The biggest risers were International Airlines Group up 12.1p to 358.1p, CRH up 41p to 1420p, easyJet up 35p to 1354p and Ashtead up 23p to 973p.
The biggest fallers were Antofagasta down 9.5p to 798.5p, Reckitt Benckiser down 55p to 5210p, Rio Tinto down 35p to 3357.5p and Fresnillo down 9p to 912.5p.