The FTSE 100 index closed up 25.43 points at 7,053.67.
Markets elsewhere in Europe were hit by a survey indicating that growth in eurozone business activity slowed by more than expected.
The latest purchasing managers' index (PMI) from Markit dropped to 53.5 from 54 in March, but a figure above 50 still implies expansion.
Markit said the slowdown reflected "weaker rates of expansion in France and Germany".
Germany's Dax share index fell 1.21% to 11,723.58, while France's Cac 40 index dropped 0.62% to 5,178.91.
Confidence among investors was also hit by Greece, as worries persist that the country may have to leave the euro.
Among shares in London, set-top box maker Pace jumped by more than a third after it agreed to be bought by Arris Group.
The US firm is buying Pace in a cash and stock deal worth $2.1bn (£1.4bn). Shares in Pace rose 34% to 447p.
Shares in WPP fell 1.5% after the advertising giant reported first quarter results.
WPP said like-for-like net sales were up 2.5% in the quarter, and said it was on track to hit full-year targets.
William Hill fell 2.98% after the bookmaker reported a 19% drop in first quarter operating profits.
The company said it had made a record weekly loss of £14m in January after a series of "customer-friendly" football results.
On the currency markets, the pound was initially hit by weaker-than-expected retail sales figures but then rebounded, rising 0.09% against the dollar to $1.5050, but dropped 0.63% against the euro to €1.393.
(Close): The FTSE 100 closed slightly higher, but disappointing eurozone data affected the rest of Europe.